Streaming doesn't break bittorrent that easily. It's not optimal for the health of a torrent cloud, but practice has shown that it's not a major issue.
> Does this mean that "unreasonable burden" is relative?
Yes, "unreasonable burden" SHOULD be relative. Not all tasks take the same amount of time.
An example I can use is a future court case that involves the safety of rockets transporting people to Mars. It becomes immediately obvious that any investigation and changes a court may demand would cost a large amount of money in such an expensive field.
It doesn't make sense for there to be a strict, absolute cap on burden, say $100000. Sure, that's the salary of an Apple engineer for the better part of the year, or several year's salary for people in other fields, but it's also a fraction of cost of a single rocket component and a tiny portion of the budget of a rocket launch for a company putting rockets into space.