Posting on the forum is free and admins are not going to change that. That will just take traffic away from Bitcointalk and increase the popularity of Discord channels, Telegram, reddit, etc. Most people have given up on the altcoin boards, and the forum staff aren't interested in policing it and deciding what is good and what is bad. Although that part of the forum is a mess, the admins tolerate those campaigns as a necessary evil because they are aware that many people are interested in that, so it generates traffic and ad revenue.

Just because some campaign purchased those BTT tokens that doesn't make it's trustworthy, and it doesn't mean it wont scam its users. And when that happens, people will start asking questions why did the forum allow that and is the forum responsible or not. That's why it will never happen.