New users often charge bellow their market rate in order to build reputation on the platform. Then once you get your 5 stars and start making good money you get banned kafka style, lame explanation, no resource.
Looks like they want to keep it a race to the bottom more than anything.
Perhaps Upwork makes more in volume if workers race bottom. Or they are really dumb. Lets hope some insider post anonymously and explain the contradiction.
It only makes sense to do that if they suspect that is the last job their user will take. Otherwise it's better to keep the user happy and keep taking a percentage for all their future work.