Removing the Alt Section would just lead to people posting about alt coins in Bitcoin related boards, which would be even more annoying.
I don't believe this is the only reason, altcoin section is the busiest section of this whole forum, without it this forum would lose huge traffic and other beneficial things and eventually fade away. You guys certainly care about it and most of those who defend bitcoin and talk shit on other cryptos (even if they are good innovative coins) are benefiting from bitcoin and don't want to see any other crypto rise. I dare you guys to delete the alt section, you won't do it and to say people will spam the bitcoin section is simply exaggeration, most of them won't care and will go somewhere else which this forum wouldn't want.
No, thats pretty much the only reason. The forums would much rather have lower traffic and better discussion. Again, its not too hard to understand, this is Bitcointalk, its primary motivation is Bitcoin, not Alt Coins, Politics, Fiat, Computer technology, etc. Those topics are just related, so whether we have a section for them or not, people are going to discuss them. Rather than delete every non Bitcoin post, each somewhat related topic has its own section so there isn't spillover into the Bitcoin related sections.
The extra resources would come from communities that would pay to have a sub forum. Also you are right in that it ultimately is better for communities to have their own forum. We all can see what a bad idea centralizing on btt would be. Forum hacked once again right. Down for a few days, cause there is no real backup plan. Imagine the damage this could do to projects to have to rely on a shoty forum.
Money isn't very important at this point. Hosting is covered, new forum software is in development, any money that is collected is essentially an emergency fund. Paying out security bounties, making patches/fixes as need arises, etc. The only real solution is to have people make their own forums. Centralization is an issue, which you brought up, but what about when moderators refuse to moderate Alt Coin sections as their individual community needs? We aren't going to make new sets of rules for each section. Don't want people trashing your coin, make your own forums and make it against the rules. There is so much drama in the alt coin scene, we have very little interest in being involved.
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Forum is already monetized enough imo. I am afraid that further attempts of selling additional 'sections' for money would have opposite effect. People would see bitcointalk admins/staff as greedy bastards who only want to make money and don't care about spreading the idea of free money and new technology. And last but not least it is primarily bitcoin forum - not altcoin. Current altcoin section is sufficient.
The only active monetization are advertisements. They are so minimally invasive, and relatively simple, there's no point in not doing them. Donations aren't being solicited, and we aren't charging for anything. The Bitcointalk admins/staff don't make the money that is collected, it is horded for future need. Even if we were greedy bastards, collection of funds doesn't help us any, so when we reach the point where any future emergency costs are stockpiled, what is the point of hoarding BTC?