If you get good members, then you win, otherwise you will not achieve the required return, although it is free and inexpensive.
The problem for devs to promote their projects on bounty boards nowadays is that there are so many irrelevant users promoting their projects, I've seen some, even the tasks they do don't get any engagement (I'm talking about social media tasks).
If your project is about crypto then yes this forum can help you a lot.
Does @Crypto_doer seem to be talking for anything other than crypto projects here? IMO, even though currently promotions with bounty programs are less effective, at least it will have an impact on the marketing side, even if only a small impact. BTW, do you know about Vulcan Forged and IOI? they did a bounty campaign on this forum a while ago, and I think they got a pretty good impact from their bounty campaign.