If our wishes include things we can not control, we will be disappointed.
We can not control what people say about our work or were they talk about it. A certain degree of criticism is to be expected, we will receive suggestions, the assholes will be present and the noobs will do their thing too. This will happen when we create a ROM, when we run a business or, tl;dr, when we do something.
A developer is free not to create an official thread here and to ask that his public links don't get posted on XDA, but if the future of your ROM depends on that, then stop wasting your time because that's not going to happen. I don't like Facebook and want people to stopping sharing "my" links there, but that's not something I can control... it's an annoyance, but I'm not going to close my website because of that.
Something we all need to understand: Links are part of the internet, they are made to be shared, they will be shared and you cannot change that.
Yes, there are lot's of wrong things with the android community. Users asking the same question over and over, users that think that they are entitled to something, users that don't even use the search before asking something, users creating offtopic... but this happens even on DU's G+ page. Yes, it's bad, but that's what happens when something goes "mainstream". Accept this and you'll have lot's of users, or create a walled garden were you control everything that is said and were only experts are allowed use your work. Developers are free to choose, but they can't have both, sorry.
There's wrong things with some devs too, many are not prepared to receive criticism or suggestions. Just because someone tells you that there's something wrong or that could be improved, it doesn't mean that that person is a self entitled piece of crap trying to attack you or your work... You don't have to agree or implement the suggestions, you can even ignore all the negative stuff, but don't expect only compliments about what you're doing. This is true for everything we do, online and offline.
Regarding XDA and DU, I believe that XDA is dealing with threads like this the way they should, after all there's nothing illegal or morally wrong with these threads. If they did something else, like banning users, then it would be a sign that it was time to move on to another place.
While I don't agree with the "share links and we drop support" thing, I hope DU returns to this forum in the future and that XDA works towards that. After all they create a very good ROM and users would benefit if they return.