Platforms/algorithms will do an "Uber" to many professions including probably my own field: presentation design. Competition/bidding to find effective market clearance. In quiet months, prices go down, you want something done tomorrow: pay for it.
For a freelancer, I think this is ultimately a race to the bottom (Godin speak). The only profitable way to build a freelance career is to work on a distinctive personal micro brand in a super niche segment, with an ever growing base of happy clients.
Maybe you use a platform to get started, but the winners will be able to wrestle themselves loose from the platform. Like the best freelancers today are often the ones that freed themselves from high paying consulting, advertising, or investment banking hierarchies.