This. It’s not like 3rd party anti-piracy firms can’t get in if they want- which is why you still need to use a VPN on public trackers- but they exist to make money with the least amount of effort, just like every other corporation. They can trawl public trackers with almost no effort, and that’s where the vast majority of users are anyway, so they’re much more likely to go after the lower hanging fruit.
key resellers have office 2021 pro plus (the non subscription one) for $30.00ish (earlier versions are even cheaper) and that is what I recommend if you absolutely have to get office.