It's very easy for it to become an issue if a game was written in Unity though. It tends to be really sluggish. E.g. Disco Elysium (amazing game) but the load screens were too much.
I don't know why but performance issues have become very common in modern games. Lots of games fail to scale to significant multiplayer populations. I still remember playing San Andreas Multiplayer/Multi Theft Auto and Just Cause 2 Multiplayer. In all three the multiplayer support is provided by a third party mod and they still managed to scale to hundreds of players per server.
