The team has clarified that commission only jobs are allowed as long as they are structured as fixed-price contracts with clear documentation of the expectations for both parties. The job in question on this thread was removed, but not because it was commission only.
I apologize for providing incorrect information earlier on this thread.
For me, it doesn't really matter what Upwork's rules are about commission-only jobs.
Because anything involving payment based on commission is not going to get past my personal mental filters. So those jobs may as well be invisible.
I'm sure that nearly all commission-only jobs posted here on Upwork are a complete waste of time for the "contractor."
For those of you who are contractors who know how to find and profit from commission-only or mainly-commission-based jobs, I guess you don't have to worry about me as competition. Commission-based income can be SUBSTANTIAL in many parts of the real-life work world. I don't think Upwork is one of those places.