they can do that without the list. as soon as you see your post doesn't get traction, make a new domain, or have multiple in the first place.

The vast majority of all posts get ~0 traction. Even prolific posters of highly-upvoted links like todsacerdoti* are probably only getting around 1 in 10 to the frontpage at all, let alone for a meaningful period of time.

* https://news.ycombinator.com/submitted?id=todsacerdoti

Have you ever checked /new? Not getting any traction is the default, not an exception. Plenty of submissions end up with no upvotes and very few clicks, hence plausible denyability.