But if you close them NOTABUG or WONTFIX, you get a reputation as that guy who just doesn't want to hear about it, what a bastard.
I think there must be a middle way somewhere, for those projects which attract a lot of interest but few or no co-maintainers. But I'm glad I'm not on the hook for finding that middle way, too.
Support is what it is, and it's a two-way street.
Most engineers usually don't have customer support or sales experience, and so don't have the experience to triage and communicate pro-socially. (I sold software as a high-school job and also had my own consultancy at 17.) It's important to push outside one's comfort-zone when young (or old) to acquire skills that will be vital later on.
Post the policies, requirments and desires in contributing.md promenently. (I think a CoC is redundant and tyrannical SJWing.) Setting expectations and not making promises is important.
Finally, there is a cost to FOSS on both supply and demand sides. I just had some company fork the repo of a project I fixed, make a pointless PR and then offer no contributions in a grsec-theft-style way.
PS: Subversion has a great talk about defending the community.
While chats can be used for that, they do not make a good job to archive the results a group discussed. For open source projects, this is essential. I often read 1 year+ old issues and they discussions are still accurate and good.
When people chat, they do not have a lot of discipline to document this. Chats are more like a conversation. They are great for two or more people to discuss something but not really good for an outside person who just gets to read the protocol.
SO is not the place to have discussions. You help people for their specific problems. You do not discuss changes there. At best, you leave a link to the issue tracker which deals with that topic.
Is this not literally the point of comments in the code?