This would be more annoying than anything, it's a pointless suggestion to be quite honest. You wouldn't need to PM someone by Steam ID. It's not convenient in any manner.
If they're spam changing it, then they'll get kicked mid-round, or you report it and they'll probably get banned. This is a limited feature you're requesting, and it's not a good one by the looks of it.
That is a good point, but we have notifications when someone changes their name and if they do it during round they are booted anyways. And if they are spam changing their name that often they are most likely trolling and there shouldn't be much you need to privately message them
