The Real Problem with CertainlyT's champions.
TL;DR at the bottom but I encourage you to read through it to understand my thought process.
CertainlyT is probably the most divisive champion designer in League of Legends right now. I've heard praise and hatred from him on all angles. I'm not going to talk about whether it's an essence of being liked, hatred or otherwise. Rather, I want to talk about a major quality CT's champions have that many other champions in the game don't have. If you need a refresher, here are some of CT's champions. I'm not counting reworks because those are created with a frame-of-reference in mind and don't accurately reflect the gameplay style he 'creates' when adding something to league:

So let's dissect a major, recurring theme.
#Darius
Darius is a big, slow, brutal juggernaut. As with any character of his type, the more range you put between him and you the better. He has no gapcloser so he's completely reliant on someone getting close. Naturally, with no "sustain", Darius is forced to take poke and be manhandled by ranged characters...but look at his apprehend. 535 range. Most ranged champions in the game sit around 550 or so. Thus, their strength is also Darius's main advantage. He takes advantage of those who go into poke. He can easily swipe up someone who makes a singular mistake. Darius is turning your strength into his.
#Thresh
Thresh is an amazing all-in champion who can toss people around like they're a volleyball. The expected weakness of this champion is twofold: One, he NEEDS people to follow him up or else he's boned. Two, he has little in the way of escaping a fight gone wrong. That's where his Q and W come in. Thresh has an incredible escape tool, so long as he can land it on something out of the fight and pull himself away. His W makes it easy to follow him up even in situations where champions couldn't. Again, Thresh has tools that circumvent the weakness present.
#Zyra
A plant who is two auto-attacks away from being turned into paper. That is, until you consider her kit: Despite being a squishy mage, Zyra has the ability to lock down anyone who gets close to her. Her main weakness, which is being jumped on, can easily be turned around and allow her to win the fight thanks to both Stranglethorns increasing plant attack speed as well as rooting targets from point-blank. Zyra has a surprising amount of options (2) for close range than she probably should (None).
Do you see the pattern? It's made even more apparent in Yasuo (Poke him down and enemy-centric movement but windwall and ganging up on him), Kalista (Close range and low base damage but stacking spears and her hop) and Zoe (Her sleep bubble being the crux of her kit but giving her tools to make use of it even if she misses it). The only champion I don't think is there is Zed, but maybe someone can correct me or has insight as a huge zed player.
The basic jist is that ALL of CT's champions, to some degree, have a way to circumvent their weakness. It's not huge in every kit, sure, but CT seems to deliberately put in tools and tricks that a good player can take advantage of to gain the upper hand. To me, this is why his champions are always so divisive and annoying to people. They break the rules of League in having counterplay to their counterplay, reliant on player skill.
Now, obviously, people are going to say this is a bad thing. I actually disagree: I think being able to counterplay your counterplay through skill is a great idea. The issue is that not every champion in League follows this philosophy. Garen, if he's kited, can't do much of anything to circumvent his weakness. If someone avoids Veigar's cage, he's kind of screwed for a bit. If you dive on Ashe, she's forced to ult or possibly die in a 1v1 fight without outside support. Because CT's champions break the rule, they're despised. They can fix their weaknesses through time, effort and skill. Other champions can't.
I don't have any grand fixer plan or expect CT to come in and go "Curses, you found my secret. Now I have to retire from Riot Games" but I do think it is something that should be discussed among the community. Is this the type of counterplay we should have in the game? Is it fair that a champion can outplay their weaknesses if the player has enough raw skill playing this character? Are CT's designs too "good" and should be toned down to allow them weaknesses within their kit? Again, I don't have any sort of comforting answer but these are things I'd love to delve into.
##TL;DR
CT's champions, unlike others, tend to have the tools/abilities to circumvent their weaknesses through player talent and skill. Other champions often don't have this in their kit and as such it makes playing against his champions feel worse.
EDIT: To address a few of the things said in comments:
#"Your examples aren't good"
Probably not. In reading back, I probably didn't word or prove my point in any sufficient manner. Many comments have picked apart my own poor reasoning and justification, which you can find below. That said, I still think the core point is a decent one. I just don't think I was able to prove it or word it correctly. I'll gladly welcome anyone who wants to better prove/disprove my point however.
#"<Competitive Play>"
This argument wouldn't work as well in competitive play because not everyone is sufficient at playing these champs in competitive play. More so, CT's champions are not always meta, which means that even if they can counterplay their problems, there are better picks that benefit the team overall. Plus, unless the champion is absurd (Zoe), pro players don't complain as much.
What I really like is that this thread has encouraged more discussion than anything on the nature of counterplay, CT's champion designs and if champion kits should circumvent weaknesses to any degree within the kit itself. Thanks guys, it's a fun thread to ready!
or/and 
- Enables mobility and engage potential where champions couldn't
- Enables misdirection with his bushes and stickiness for an individual champions that could've otherwise been out of reach
- Cross map teleports allowing follow ups and flanking maneuvers that are impossible for many other champions
- Headbutt can throw enemies back into allies
- Leaps to other champions, an ability matched only by Rakan, potentially amplifying their engage potential
- Monsoon can throw enemies back into allies
- Team-wide AOE speedboost
- Not really a support but an AOE speedboost and MASSIVELY enhanced engage potential for allies
- AOE speedboosts
- Throws enemies back into team and can cut off enemies
- Invincibility allows all sorts of follow up potential to champions
- Allahu ackbar
- Not a "support" but is defined by his pull
