From the "Congested Server" web page:

"New characters cannot be created on Congested Worlds."

So:

1) I have an account and I have a character on it that I can log in.
2) I can only play one character on the account at a time
3) If I log out of a character that exists I can log into another one that exists
4) If I log out of a character SE ban me from creating a new character on a 'congested' server.
5) SE define congestion as the number of PLAYERS actively playing, which is totally unrelated to them logging into an existing character OR creating a new one.

So explain to me SE why this ridiculous banning of existing players being able to create a new character on a server they already HAVE characters on.