I'm assuming 50 or so ping is fine for most ranks until you get to much higher elo yeah? I'm also factoring out certain champions who need incredibly low ping to pull off intricate combinations as they aren't all too essential until said much higher elo.
It should be obvious, but it depends more on the champion than the level of play. 
combos are virtually impossible to get even remotely frame-tight outside of LAN play, and 
R tricks become undoable around 100p. Someone like 
who's mechanical intensity comes from buffered spells though, wouldn't be nearly as affected.
Adrian Riven plays Riven and Fiora with 70 ping and consistently hits top 10 challenger.
Id say it's not as important as people think, as long as it's not like 120.
It's not really the rank that matters, it's the champion
Ping doesn't matter much. The best players can play on 140 ping.
I can start noticing delay at 90ms
One of my friends plays in d2 and they have 200 ping.
I play at 100 with random spikes and dcs and have been in d2 elo, but its true that it feels anoying and make you lose some games.
High diamond I assume.
I have an account on EUW and have no trouble playing high gold-plat ranked matches with 130 Ping.
It just takes a lot more prediction based gameplay because I can’t react fast enough with that ping.
It starts to become a pretty big part in your game around master elo. People really start to take the game seriously at that time.
