Earlier quoted context omitted.
Yes, milking the lower end is just unfair and will obviously create resentment in freelancers. A really long time back I complained to them that their fees were unfair (I think about the time when eLance and oDesk merged). And their reply was educational to me - "Why are you paying the fees? Bill it to your client or share the cost with them?" . And I did start doing that. Few clients were ok with that because the <$…
All fees get paid by the customer in one way or another, it's just how it's advertised and how you think about it. With business-related things it's better to have it upfront in my experience.
In theory only partially if the freelancers are competing with those who are not using the platform and just bill their clients directly.