There is a simple solution to remove farms (or atleast majority of them)- introduce Jr Member as minimum requirement but that won't happen of course due before mentioned reason.
You're right most Altcoin bounty managers don't think much about the account farms in their campaigns. but of course, some still care.
I agree with the minimum JR Member rules that the bounty manager may adopt. or at least for some campaigns like Signature, Article, or Video. while Newbie accounts can be on social media with a minimum of activities that have been achieved.
the problem is, is it possible that the bounty manager is willing to apply such rules? at the risk of client satisfaction that may be disrupted.