They do! All of these backbone comply with takedown requests. Some comply with DMCA requests only, some comply with NTD requests only, and some comply with both. It's actually another thing you could consider when selecting your providers, you check their takedown policies. By mixing and matching, you increase your chances of finding every part of your file.
So, the thing saving usenet in particular, is that the pieces of the file get scattered through the usenet, and you require indexers to find the whole thing. This makes it difficult for takedown requests to actually take down the whole file. Sometimes the best they can do is remove a few parts, and you can repair your file with what's left. Sometimes they do win, but it happens infrequently enough that you should be able to complete most of your media library without issue.
I'm relatively new to usenet myself and have both torrent and usenet tied to my *arr automations. From what I can tell, for newer stuff they're less distinguishable than for older stuff. Things basically get uploaded in both places for the most part, so you can also get duds on usenet, the same duds you'd get on torrents.