That's what I do and it works great for me, most of what it grabs comes from 1337x, nyaa.si, torrent Galaxy, one of the kickass clones, extra torrent, and piratebay. I don't use private trackers or Usenet at all. Same with sonarr. Both are hooked up to prowlarr which makes it so easy to add new public trackers in a few clicks.

Actually for the first several years I just used sonarr/radarr for renaming and getting insight into the composition of my collection (ie checking series completeness, finding stuff I wanted to upgrade, etc). Only in the last few years have I actually started using it for download automation.