We aren't trying to limit anyone from talking about an altcoin, we're trying to limit the altcoin spam in Bitcoin sections
Altcoins exist and their market share is growing. So dedicating a space for them will decrase the spam in the BTC sections.
This site is "bitcointalk.org", not "insertaltcoinheretalk.org". I'm working on a solution for communications regarding alternative coins, but it's not done yet.