yes, an exchange would hold similar power if fiat was desired at all, but it wouldn't prevent the crowdfunding from taking place. and because the crowdfund would still occur, the recipient can find an exchange or trade desk that would do the trade for fiat. right now, fiat crowdfunding sites are acting as the platform and exchange while being beholden to a payment processor behind the scenes. in the crypto model, the platform is just a GUI over something that can be interacted with either way, and the exchange is separate and optional.

so because there are trillions of dollars in crypto value already and many individuals already own that crypto, they would just collect from them to their own address or smart contract. websites just become GUIs for helping that and are also optional. then if fiat is actually desired for the cause, they can call any random trade desk and do a big order for fiat and have cash in the organization's bank account. for their supporters that don't already own crypto, it would be some friction for them to acquire it, but forget about those people and don't view how it would work from their perspective as the main perspective.