> but if a library is repeatedly releasing one broken version after another, you probably just shouldn't use it.

Your assumption here is that it was the boring-library version 1.5 that was broken, in reality it could be that they changed something that wasn't documented and was only an implementation detail, but was relied on by cool-framework (e.g. getting a list back sorted in one particular way in 1.4 and sorted in another way in 1.5 where the order was never part of the API contract).