As a bounty manager, in whose campaigns the three-phase payment method is used quite often I can express my opinion on this issue. I had 3 such campaigns, Ferrum Networks, Cartesi, DIA, all three projects are successful (it is not yet possible to say for sure, as the DIA distribution is ahead, but the fundraising is good). Besides, I had many other campaigns with another form of token payment and some of them were unsuccessful.
What are the advantages:
1. The team is worried about the price of tokens on the exchange, so they are going to develop their project in the future.
2. Potential investors and advisors will pay more attention to the project, because they invest their money and do not want the bounty hunters to get a bunch of tokens "for free".
3. Unfair bounty hunters will not be able to immediately drop the price after receiving their tokens. Despite the fight against fraudsters in any campaign there are always those who could not be detected and banned.
4. Bounty hunters will be able to sell their tokens on a higher price or even hold them, stake or use for mining.
What are the disadvantages:
1. Bounty hunters will need to wait longer to receive full payment.
In general, some of participants are constantly complaining about that, I can say only about my campaigns: Distribution terms are always announced from the beginning. IF you're uncomfy with them - do not join.
Some saying that project can scam members and do not pay them - I can only say that if project fails or ended up scam you will not get payment anyway, with one-time payment or three phase payment. This is not the only payment method, and most likely not the best, projects and campaigns have very different conditions. However, my main thesis is that a project and a bounty campaign are not bad because of payment methods, but for other reasons.
My personal advice to all hunters - always check project carefully and read every single word written in bounty thread, otherwise you will end up asking why you have no rewards.