It has always irked me that people are unable to differentiate between comparing two things and equating two things. Despite being completely different actions, it's commonly accepted to treat them the same. This leads to all sorts of misconceptions and invalidates plenty of reasonable points.
It shouldn't be "provoking" or "uncomfortable" that any two things share some similarities, because everything shares at least some similarities with every other thing. That doesn't mean other properties (e.g. the evils of slavery) of those things automatically become transposable.