Why are ICO's being advertised? I could go on, on how a part of this forum has nothing to do with bitcoin.
I'm just mentioning something fun most people can possibly relate too.
ICOs aren't officially being advertised by Bitcointalk. People are just using Bitcointalk to advertise ICOs through posting in the Altcoins(Announcements) section. Two quite different things. Not to mention adding the feature of being able to buy tokens is going to be tedious as heck; as there are so much tokens being advertised here on Bitcointalk. If bitcointalk would sell anything, it would be bitcoin and bitcoin-related merch/collectibles.