Resource and Mobility.

Is there a particular reason High Mobility Characters like Yasuo, Riven, and Zed use energy and not mana? I mean, mana is essentially a means to limit how long a character can be in lane before backing, this prevents characters like Swain or Viktor from completely stomping their lane, since they are limited early on by their mana supply.

Now, I understand that there is counterplay for every situation, but with how strong Lethality is right now, assassins are running rampant, and this makes mid lane a very scary place for mages.

Pair the seemingly overpowered lethality builds with Yasuo and Zed's free mobility together, and you get an anti-fun cake. As far as Riven goes, her mobility kicks the pants off of the other two, to the point of sheer absurdity.

Granted, you have to know what you're doing to not feed out your ass, but if you manage your cooldowns, you can mess up, and get away with impunity because very few people can keep up with you. (A jungle Warwick is probably your best bet, honestly)

The three of them are worse than Heimerdinger when it comes to anti-fun, because Heimer's turrets are worthless in late game, where a single shot from most adcs will kill it instantly. Heimer is annoying as all hell early, but becomes irrelevant in late because everyone out scales him.

Yasuo, Zed and Riven are just as strong early because they are not limited by mana, and only get stronger as the game progresses.

Mana is meant to be a limiter, so why exactly did Riot opt to not limit the three characters with the most mobility?

Alternate resource bars in general are strange, but I only bring these three up because they seem to benefit from lethality the most.