I believe that the participants in the bounty have a positive effect on the dissemination of information about the ICO project. But with an unregulated large number of participants, their reward in the companies of bounty social networks is very small. Also, despite the fact that the reward is 1-3% of the total pool of coins, the influence of the bounty participants on the value of the coin of projects after entering the stock exchange cannot be critical.
I agree with your opinion, bounty hunter has a positive effect on the development of the project introducing ICO to public, so they know about the project. I think the allocation of coins / tokens is given to bounty hunters, the percentage is very small from the total coins / project tokens, so I don't think it has too much influence on the price of coins