A way to get a specific player’s SteamID

[Hichatu]

A simple getter function such as .GetSteamID() that would grab a specific player’s SteamID.

Was previously possible with the player_connect game event.

This would allow custom maps to give special rewards and goodies to specific players (for example contest winners).

[Faramour]

Additionally this could be used to store information about user in a way that persists through players leaving the server.
Example: a map that has RPG system. Normally, information about player such as level, stats or custom items would be lost for that player when he leaves the server. He'd be reset to default stats and no items on connection. Storing information with SteamID would allow to check if player already had stats during current map's lifetime and assign them to him after connection.