Selfish laners, trying to dictate what a jungler's role is. You think that just because a champion isn't ganking your lane that they're not doing their job?
There are three types of junglers.
Ganking Junglers - Junglers with CC and high mobility, who gank lanes and attempt to snowball every other lane in order to win hard in the early game and press the advantage. In theory, this role should be the highest risk, and the highest reward.
Control Junglers - Junglers who attempt to shut the enemy jungler down by denying XP and gold via counter jungling, and preventing successful ganks by establishing vision in the enemy jungle. In the current iteration of the jungle, a control jungler wins by surviving the early game pressure of a ganking jungler and controlling objectives (baron and dragon) to snowball the entire team rather than just one lane at a time. In theory, this role should be the medium risk, medium reward.
Farm Junglers - Junglers who have strong capacity to carry the game on their own, but for various reasons in their kit, do not function well in lane. Rather than applying early pressure, they get their machete upgrade quickly, and farm up a large amount of gold by focusing on clearing as many camps as possible as quickly as possible. They win in the late game, same as a marksman would. In theory, this role should be the lowest risk, lowest reward.
So there you go. You have an early, a mid, and a late game jungle style. In a perfectly balanced system, Ganking Junglers counter Farm Junglers by applying so much map pressure that they win the game before the farm jungler hits their power spike, Control Junglers counter Ganking junglers by shutting them down so hard that it becomes a 4v5, even when the enemy jungler has gotten his team a few kills, and Farm Junglers counter Control Junglers by clearing their own camps faster than the Control Jungler can, resulting in a Control Jungler who can do little to affect the outcome of the match.
The problem is that Riot has heavily favored Ganking Junglers since the inception of the LCS, because Ganking Junglers are much more active in the early game and therefore more fun to watch. They also interact with the enemy team more often than control or farm junglers do, and that makes it easier for the enemy team as a group to fight back against them, rather than it just being the jungler's job.
So, what's the problem here? For starters, ganking junglers benefit greatly from mobility creep. They become harder and harder to defend against when they can gank from all kinds of angles that you can't get a ward to, like Zac's Slingshot or Rek'sai's Void Tunnel. The big problem is that Riot has introduced the trinket system, and because of that, players have guaranteed defenses against ganking junglers, which means Riot can in turn make ganking junglers stronger in order to balance out the increased defense players have with free vision. But it's become a self-defeating system, especially when the laner is under so much pressure from the enemy laner that they cannot even use their trinket.
So, ganking junglers get stronger from mobility creep. What about control junglers? Riot has nerfed control junglers several times in the last few seasons. For starters, you need to clear an entire camp to hit level 2, so a control jungler starting the game off with a buff steal has become very risky and ineffective. Secondly, the Poacher's Knife item is very ineffective at helping control junglers do their job properly, and what's worse, it telegraphs to the enemy team that you're going to counterjungle, which allows laners to play more aggressively and also encourages the enemy mid laner to keep an eye on the map so he can assist his jungler in the jungle and get free kills.
And then there are farm junglers. The problem with farm junglers is that they are, by their very nature, low counterplay assassin type champions. And when those champions get fed, they become a problem. LeBlanc, Zed, Fizz and Ahri are in similar positions, but they have to lane in order to get their power spike, which means they are subject to jungle pressure and lane harass, so if you lose lane and they get fed, it feels fair to you because you had a chance to stop them. Yi, Udyr, Shyvana and Warwick just kind of...farm. All day. The counter to that is trying to get them in their own jungle, but...they have vision set up, they have laners and towers to help them escape, and they have no real punishment if you manage to chase them out. It's like Nasus, except that Riot actually decided to do something about it.
So, Riot wants ganking junglers to be strong, so rather than having a balanced system of counterpicks and counter strategies, we have "Who can gank harder". Same with supports and the lost trinity of sustain, poke and all-in.