Some of your reasoning definitely rings true, and you touch on one of the issues I have with it all: Most people don't have "autonomous" accounts for each tribe they belong to... which creates the situation in which you might be downvoting something on Hive for an unrelated reason, but because that post happens to be using the #proofofbrain tag and your account also happens to contain staked POB tokens... suddenly you could find yourself inadvertently breaking guidelines.