TBH bounty hunters don't care, the moment you said you won't join a bounty because of too many participants or lack of limited participants rules from bounty manager many will still join the bounty, this will be so effective if bounty managers can become one but .........
You are right and even if the bounty thread has an accusations of being a scam or whatever negatives issues it has bounty hunters still joining most specially newbies who do not care anything. And having fixed allocations for bounty participants don't guarantee hunters a profitable rewards cause it would still depends on the price value of the tokens.