Mobility creep came about because ranged champions were able to kite melee champions making melee useless now if you want to remove mobility creep the only way to fix it is to add turn-rate that way champions can't kite and it makes it so we can remove mobility creep DotA 2 has turn-rate and they don't have heroes with 7 gapclosers and a ton of CC if we want to remove mobility creep from the game we need turn rate to be added.
While it could potentially solve the mobility creep, it feels sluggish (and god, the hell when you fight against Batrider) and I don't think it would fit in League which always (AFAIK it was like this from beginning, I play it since S2) was more about the faster combat with more actions and less (or at least shorter) CC.
I am not saying that DoTA is a bad game, or that it's worse than League - but they are different by now. What works in DoTA won't necessarily work in League - and I don't think that turn speed would work. There are more ways to fight mobility creep, like:
Ranged Champions
Ranged champion with mobility abilities (or passives) should have some major drawbacks in one or more of the departaments (or better yet - they should not exist):
Melee Champions
Melee champions should also pay higher price for having mobility - especially excessive mobility, like Lee Sin, Zed, Yasuo or Riven. Again, touching their base stats and abilities would be the easiest solution, but I would also like to add that a mobile champion should never be completely resourceless. I mean, mobility is already hard to gate - how are you going to do it without resource? The only way I see possible, is to give it very high cooldown, but then you have Yasuo with his 0,1s cd E... Outside of this, tanky champions with mobility should pay with offense or utility and squishy champs should pay with defense (so that if they do make a mistake they will actually feel it).
Items
There should be more itemization to fight mobility creep, like an item that speeds you up everytime you get hit with ranged attack or single target spell or some hard CC effect on an item. Of course, the second one would be tough to balance, but I think it could work with a Snare/Root or even a completely new status effect that disables mobility spells (just like snare does, but without the actual snare effect). Name it shackle or something.
Slows
They should be a bit less common (nearly everything have a slow in this game right now) and should be less potent (A huge amount of slows with values around 60-80%, a few ones with over 100%, Nasus W for example have 110% slow, Rumble E can have 105% too, if cast while in danger zone). They make walking really useless, especially combined with items that can give permaslows (30-40%) and red buff which gives 25%/15% or so (rmelee/ranged).
However, I think they should also work on non-blink mobility spells (dashes, jumps etc). While decreasing their length would be rather hard to balance properly (all those jumps over the wall etc) the animation and speed could be slower, giving more time to react and stop it (I think Yasuo E works like this). Could work with 50% of slow effect up to a 35% cap (so if you have 70% slow, the dash speed would be slowed by 50%).
Flash
A small cast time (0,25s?) with a bit improved range. Either interruptable (with significantly reduced CD if it was interrupted, like 20s) or not - it would make a big difference.
However, I doubt Riot will do anything about it. You know, mobility spells look flashy and make for big plays (also every Orianna ultimate is a big play too for some reason).
