There is no report button. If you want the mods to make the site less xyz, email them a link to the xyz that you came across and say you want less of xyz, either specifically and/or generally. Let them decide how to respond; that’s not your problem, no need to invest effort in it.

‘flag’, if that’s what you mean, only sends a mathematical algorithm signal, that does not lead to mod attention. I flag posts that are dupes, irrelevant, low-effort, or are hard paywalled without a bypass link. This is often sufficient and is like sweeping cobwebs out of an ignored corner: it’s not worth getting upset about, just grab the broom and sweep it up and move on.

I email mods for issues that I think should be addressed to keep HN a better place than the voting/flag algorithms can solve without human assistance: guidelines violations like high-karma users insulting others, or patterns of behavior observed unflagged over time, or suspicion of voting rings; or technical issues with the xyz.com/subdomain detector that prevent self-linking detection from working, or with the auto-dead-ifier that’s the topic of this post, etc.

tl;dr nope, the mods monitor emails not flags