Why would P+ allow the same people who can't hold on to their current audience do another show?
After Jaws and Close Encounters, Steven Spielberg had a massive flop with 1941. But he followed up that failure with Raiders of the Lost Ark and E.T. The first four shows Dick Wolf created were all short-lived failures, but the fifth one was Law & Order.
Nobody bats a thousand. It's a competitive industry, and failure is always more likely than success, so if everyone who had one failure was blacklisted, there'd quickly be nobody left in the industry. There are a lot of reasons why a show or movie might fail that have nothing to do with the ability of the creators. Failure is a learning experience, and experience is always valuable.