Why does Riot encourage snowball mechanics??

I mean, there so many champions, and things in the game that get beyond ridicolous if they get just a little bit ahead of you.

First of all, the Devour new jungle item. Im not saying that he is super mega op and stuff, but on SOME champions, if they get a little bit ahead of you, that's it, you lost the game pretty much. Im talking about Udyr,Shyvana,Fizz, Master yi. Fizz with devour and some items, can 1v5 your team. How is that fun or balanced?. Same goes for the others

Then there are champions that in lane, become extremely difficult if not downright impossible to deal with, if they get a lead. J4 full AD, Riven, things like those, they have a kit that permits them to assassinate you without any chance of reply.

I repeat im not saying that it's IMPOSSIBLE to play against them, but what im saying is that these mecanichs are anti-fun. Someone with a lead should clearly have an advantage but sometimes it become just so ridicolous that it's almost unbereable.