I play League of Legends and have only DSL but my ping is only 35 ms and I can't complain -- many other players have it worse than me.
What did make it impossible for me to get kills was having 30 ms of latency in my display system. I think the network latency is well-compensated (if the typical user has 50 ms of latency, just delay me by 20 ms) but the display latency kills me. When I switched to a different monitor I started playing much better in about five games.
I think the game generates a 10 MB log for a 30 minute session so the bandwidth requirement is not much.
I had the same experience playing Titanfall earlier; in that case turning on the "Game Mode" on the TV turned me from someone who couldn't win at all to somebody who could get halfway up the ladder.
Display (and input!) latency are real things, and matter quite a bit. There have been studies in the past where people measured the full button press to frame update time using high speed cameras, and not all games are equal. As for game mode on TV's, that specifically why it exists. As a passive medium a little latency doesn't matter, but when a system is responding to input, latency is noticeable.
If you're interested in how different TV's perform, segregated by their individual input ports (in cases where some ports are optimized) and modes, check out https://www.rtings.com/. I used it a couple years ago to pick out a good 4k TV as a monitor, and the very thorough information helped me pick out something that works well as a computer monitor (and also for the occasional gaming).
How does 30ms of display latency affect LoL gameplay? I don't play it, but I've seen videos of it a few times and with it not being a FPS I wonder what aspects of the game are that greatly affected with an additional 30ms of display latency.
Mind you, any mouse lag drives me up the wall. I've never measured at what point I perceive that mouse lag, but it's a fairly low number I'm sure.
What did make it impossible for me to get kills was having 30 ms of latency in my display system. I think the network latency is well-compensated (if the typical user has 50 ms of latency, just delay me by 20 ms) but the display latency kills me. When I switched to a different monitor I started playing much better in about five games.
I think the game generates a 10 MB log for a 30 minute session so the bandwidth requirement is not much.
I had the same experience playing Titanfall earlier; in that case turning on the "Game Mode" on the TV turned me from someone who couldn't win at all to somebody who could get halfway up the ladder.