[Unpopular opinion] The reason why mobile champions are annoying is because they dont lose anything.

Let me explain what I mean.

Let's say that there's a champ, for example Darius. He deals 300 dmg on his Q and 200 dmg on his W (I know that's not true but that gives us some numbers to work with) and suddenly, Riot decides to rework him, his W is replaced by a non-damaging dash. Technically, that should mean that Darius loses his 200 damage IN EXCHANGE for mobility, however, what happens is as a compensation, the 200 damage get added onto his Q instead.

So now, instead of having 500 damage spread over 2 spells, it's spread over 1 spell which not only decreases kill time (1 ability takes less time to land than 2 abilities) but also "frees up" the W to be changed to something else.

But does Riot do that? Well, the answer is yes.

Some of the most mobile champions are assassins, they are also famous for ridiculously low kill times, let's investigate one of them: Rengar.

Rengar's main damaging ability is his Q, the rest of his kit is more or less utility, this allows him to have such huge burst on his Q. Now, the problem with that is the fact that some other champions take 2-3 abilities to match the damage of Rengar's Q, but Rengar isn't even a mobile champion, take a look at his nemesis: Kha'Zix!

He has the same thing, his Q deals a chunk of damage while he still keeps a long leap, up to 3 invisibility charges and a slow. Let's talk about a champion I know well: Renekton, who has a double dash, a stun, a heal and loads of other stuff, his kit is well designed because he has to land his E, autoattack, W, autoattack and finally Q before dashing back out, all those abilities deal damage which adds up to Renekton's trade.

On the other hand, most mages are experts at burst damage, but it's also OK, because that's what they have, damage and that's it, if an Ahri or any artillery mage + Lux bursts me down in 3 seconds, using their entire kit on locking me down and killing me then they deserved it, if a Kha'Zix leaps around the map and is invisible before catching me out that's not okay, simply because Lux has to use her entire kit to kill me, while a lot of assassins use one or to spells then dash away unharmed.

This is all because there are champions whose kits are extremely overloaded and this allows them to have a plan for everything (use plan A, if doesn't work use plan B, then C, then D, etc...), if someone has a lot of things in his kit, he shouldn't do better than someone who is a specialist at one of those things.

TLDR; Generalists with overloaded kits are outperforming specialists because they have too much of everything, instead of being decent at everything, they are brilliant at everything.