Every now and then people use an extremely long name like
When play with this guy, his name will cover on the map and make other player cannot see the map.
I am using a standard 1920 x 1080 screen and I think it affect quite a lot of people
Knowing that the game uses your Steam name (or from another platform). Limiting the name is up to these platforms, not to the devs.
What is up to the devs is how many characters they could show of a name. That would be a more sensible suggestion.