There are a few different things I'd like to mention:
- I don't think, that there is such a thing as a massively defederated instance exists right now. The most blocked instance is blocked by about 11% of the instances, followed by two instances at 6%
- Even if the die hard scene users would know their instances, not every random troll or spammer would.
- This doesn't address the possible legal issues of publicly announcing where someone could find illegal content
- If "small queer instance" refers to beehaw... That's the second largest instance there is as of today according to https://github.com/maltfield/awesome-lemmy-instances
And lastly: If you're new to the fediverse you maybe shouldn't run your own instance in first place. Helping reckless people pull reckless stunts is a bad reason to promote a feature.
Since this was a question about a lemmy feature, I'm talking lemmy here, arguing about fediverse, TCP/IP or electricity numbers/servers/plants doesn't seem usefull in this context. Providing a link to a server that to your knowledge (you provided the reason) hosts illegal content can be seen as participating in this crime or at least advertizing. (Disclaimer: I'm no lawyer, I just remember whole BBS being seized for providing lists of (international) phone numbers to BBS that hosted warez and there's stuff that's worse than warez).