@ben right now, with meta and other firms restricting transparency, it’s hard to know what the effects have been. From news publishers, it’s clear that the reductions in news promotion have hurt public knowledge and journalism for years.
I am hoping that the DSA and related laws will create the conditions for more fine grained independent evaluation of platform policies, which is why I am working on that issue now. It really sucks not to be able to answer the most basic questions.