[gpm]

The largest straight line distance across the US is 2802 miles (Florida to Washington), according to the internet. That's 15 light milliseconds in a vacuum. That's roughly a frame of delay at 60fps. You need to multiply by another 1.5 to account for the speed of light in fiber, and fiber doesn't go in straight lines, but at the same time datacenters and users are unlikely to be literally as far apart as possible, so let's pretend those cancel out.

You don't need to be across the world for it to matter, just across the continent.

[earthtourist]

Yes, and no one should try to play competitive games across a continent. Competitions must be regional. Internet latency is great within a few hundred miles.

[gpm]

This isn't a question of where the players are relative to eachother, this is a question of where the players are relative to the datacenter with tons of expensive GPUs. Also for many games where that datacenter is relative to the game servers.