I'd say Ron Moore's tirade over Voyager makes a convincing argument that those two were part and parcel of Trek jumping the shark. Just because the execs also made bad calls doesn't mean the blame should just shift over to them.
It means that instead of falling for the simplistic allure of blame, we should recognize that creating television is a complex process with a lot of hands involved and can be difficult to get right even when everyone is sincerely trying to do their best. Now, I agree that Braga was probably the weakest Trek showrunner of the modern era, not counting the aged, infirm Roddenberry himself in TNG season 1. And I believe that Berman was a much better logistical producer than he was a writer. But I also think that both of them had good ideas as well as not-so-good ones, and we should be mature and honest enough to recognize that people are capable of doing both good and bad work in the course of their careers, rather than reducing people to caricatures of incompetence just because they made some creative decisions we didn't agree with.