Unfortunately a lot of trackers do that :dabs:. If your inviter suddenly decides that his invites are better spent in trades, you could end up being banned at no fault of your own. I guess in the BT world it saves more time to decide "guilty until proven innocent" so staff will automatically assume the entire tree is filled with traders/rule breakers.
I would imagine they usually are, and yeah, I can see that it would save a ton of time just banning the entire tree rather than waste countless hours researching each member to determine his/her innocence. If someone truly was innocent and caught in a case like that, a quick trip to irc should clear things up provided they've been a decent and useful member of the site up to that point.
I think it raises an important point: that people should take care with who they accept an invite from, just as they would if they were offering one. If you're going to accept an invite from someone who cheats or trades invites, then you should expect that you'll be associated with that person, and could possibly be banned due to his actions.
