To add onto that, a game can use a custom leaderboard that removes moderators from the playerlist right now without any features required on ROBLOX’s end. Hiding players can be done without hacks like parenting players to nil, so that’s definitely not a reason to keep that behavior around.
If the reasoning was something like “moderators free up a player slot when parented to nil so others can join” or “players can see you in the server from the site”, you still show up in the server list in that server, and you still take up a player slot, preventing someone else from filling it.