If you want to make it harder to hit, you have to take off resistances, if you want to have more mobility, you have to take off damage or hp. Having everything in one package is just bad.
This is a new game. They dont have to follow identities or gimmicks created by people over time.(tf2, dota, cs) Also everything you see in other games doesnt make it good, its just not as bad to take it out or make substitute.
There are no root item to prohibit stamina spam, and stamina are accounted for in game balance by devs, and you have to invest to get more, and you getting only stamina with little off stats, also its taking less desired for it slot of vitality category. Balanced mostly.
Slowing only affects movespeed and tied to it abilites like infernus second ability. Dashes and jumps has fixed movespeed during it, that's why people can slide after them (slowing doesnt counter stamina)
Try to play against people that abuse movement, really annoying and little to no counterplay (slowing hex doesnt solve everything and too slow to apply in offensive situation).
There is also shiv who can imitate rocket jump with alt fire or majectic jump, jump slowly becoming a problem.
Its a problem when things overlap. Pocket is already hard to kill without applying silences in a row or killing him in a single cc you somehow applied. Same with other mobility heroes. They possess same damage capabilities as others, but have more ways to dodge bad situations. Which is bad due to them buying all mobility items, therefore increasing their mobility even more. Not to mention ongoing lane skip with majestic jump.
Why would you make one class even better without buffing another? This item would not be used by heroes without innate mobility, they have no uses for it.
Also there are mo&krill second ability which makes your hitbox small and gives resistances, it takes away ability to shoot and use two others abilities, which is good enough trade off if you want to make hitbox smaller in his hero design.
Difference in hitboxes is obviously tied to hero game role, stamina substites mobility and so some heroes have more.
Until they fixed majectic jump and solved mobility abuse this item is going to make game state worse.
If you dont see it as a problem, i cant make you to see it, i can only suggest to watch lash / dynamo / pocket / etc players that are really good.
