My self hosted mail server is averse to anything with a low bar to entry. When a registrar rents thousands of domains to a group for nearly free they get added to a file that will just REJECT them with a URL or snarky message. There are a handful of TLD's that my DNS will NXDOMAIN as well. I have done this for decades and have zero regrets while acknowledging it is hard for people to get a decent short name on .com net org. IRL and internet scammers are why we can't have nice things.