They were designed to stop people monetising their property like Axanar (and Renegades, to a lesser extent) were doing.I'm just coming across this Axenar/lawsuit/fan fiction guidelines from 2015 and I'm stunned at how ridiculous they are - no more feature films? Limits of 2 episodes per series?? Is there a summary somewhere on what the reaction has been since then? I would expect a lot of ppl would boycott ST, paramount+, etc, until they revised the fan fiction guidelines. But maybe no one cares?
And it failed at that, because Axanar has continued to do so (albeit to a much lesser extent) until the present day.
To the best of my knowledge, they've come down on one fan-published book for using screenshots of episodes (and selling Star Trek books, which S&S have an exclusive license to do) since then and zero fan films.