The dumbest thing in this community is the concept of ragequitting
With regards to the topic title, I do not mean the ragequitters themselves. I don't have a problem with anyone who leaves a game early because of an impossible to win scenario. My problem is that these people are demonized and vilified. Someone even posted a thread to say they had started a site for a banlist of people who ragequit. Leaving/conceding a round that you are most definitely going to lose is acceptable in every other game I've played and this is the reason most people leave a round early. There are a few who will leave before the game is decided(and yes these people screw their teams over and I don't like them anymore than you do), but they are not nearly numerous enough to generate the number of complaints and attitude I see around here.
So what happens in demigod because of this attitude? SomeRandomNewbie starts playing demigod. He doesn't come from DOTA or wherever the hell this ridiculous attitude spawned and sees no problem with leaving when the winning team has an irreversible edge. Maybe he even thinks the replacement ai will actually do better than him. He loses his first few matches for whatever reason and leaves them all before his citadel is actually destroyed. Someone he played with starts telling everyone that SomeRandomNewbie is a ragequitter. SomeRandomNewbie starts getting kicked from games for a reason that doesn't even make sense to him. SomeRandomNewbie stops playing demigod because as far as he's concerned, the community is utter trash. This is a completely plausible scenario(I've seen hosts kick when someone just accuses a connector of being a ragequitter) and if it starts happening consistently, it will stagnate the growth of the community. There are a few things on gpg and stadock's end that need to change as well but the community side is more important. If things like a concede button are added but the stigma of leaving remains, they will achieve nothing whatsoever.
Even if you don't change your attitude, you should at the very least change the way you approach this issue. Rather than coming on the forums after the fact and bitching that player X fed the enemy a billion gold then ragequit, you should ask people to stay in the game even if it looks like your team is going to lose. It is no different than asking your allies to cooperate with you strategically. If they just ignore you, then at least you know that you're blacklisting an asshole when you complain about them to others.