I think google and PayPal have shown every companies in the valley that you can be unreliable and stonewall your users without hindering economic success.
They're being unreliable and stonewalling an extraordinarily tiny percentage of their massive userbases. That's precisely why it doesn't matter to them in a business sense.
PayPal froze my account a few years ago for "suspicious activity". I still don't know what that activity was. Support gave me the same sort of runaround non-answers as described in this article. I finally got to talk to someone on the phone and had an exchange along these lines:
me: "Is there any way I can continue to use paypal?"
paypal: "You can open up a new bank account and then use that to register a different paypal account"
me: "..."
While I agree that those companies and many others have become quite successful taking this tact, it was really only successful because of those businesses are nearly monopolies. Obviously this is similar to ISPs. Upwork competes with tons of other boards directly as well as LinkedIn, Indeed/Job Boards, Craigslist, general networking and other preferences (not working an additional part time job).
Also, similar to recruiting these places need to attract top talent consistently not just warm-bodies. Highly skilled workers can afford to exercise other options much better.
You're right, but upwork is the dominant marketplace for low-cost contract labor. It is the merger of what was previously a duopoly in the space (elance and odesk) and the network effects are strong.
So maybe it's not quite as monopolistic as the others you mentioned but it has clearly (and rationally) chosen to compromise fairness to its users to a degree that it likely could not in a more competitive market.
They're being unreliable and stonewalling an extraordinarily tiny percentage of their massive userbases. That's precisely why it doesn't matter to them in a business sense.