I mean if you think the treatment of contributors is harsh, they pale in comparison to how harsh the team is on itself and some of the epic squabbles that have happened. Working on big projects generates a lot of creative friction. It's the nature of the beast. It's actually a good sign because it means people really care. There's more to worry about when people stop caring and just shrug and let anything go.
It's true there's also a "democracy ethos" as another way. T2X had that. It wanted to let everyone participate, and it's another valid model and has its virtues which were on display in that. But it also suffers for it in other ways, quality, consistency, and there's still interpersonal friction. But anyway it isn't our model, at least for the core stuff. We just picked a more closed model from the start and stuck to it. We're very democratic when it comes to FMs though.
And I think people that want to enter any creative endeavor seriously should learn to grow thick skin, because you don't get better unless your work is subjected to the cruel light of day under a microscope, keeping in mind the real world limitations. And as I said before, skepticism is almost the reflexive first reaction if someone expects something to go in, but it forces you to expect high standards. My first project was the ambient sound system, and I got skepticism and pushback. But it was good because it forced me to make the system as perfect as I could. 'I'll show them!' It wouldn't have gotten to a workable state without that push. And in the end, I'm proud that it's used a lot.
But anyway, all of this assumes there's no safe place for newbies to make stuff just for fun with no pressure. There is a place for that in FMs, and we can find examples in the forums all the time.
Edit: We're friendly towards newbie mappers with FM contests. We could have an asset contest or contribution drive friendly for newbies for our "Fan Contribution Depository" too. That might be a good way to give some attention to it and make a depository actually work & get maintained. And just generally, it might be constructive to treat fan assets like fan-missions. There's a valid point to be made that fans should have encouraging & newbie-friendly outlets to contribute to the game.