https://en.wikipedia.org/wiki/MDPI#Resignations_of_editors
In August 2018, 10 senior editors (including the editor-in-chief) of the journal Nutrients resigned, alleging that MDPI forced the replacement of the editor-in-chief because of his high editorial standards and for resisting pressure to "accept manuscripts of mediocre quality and importance.
I was "around" science for a good chunk of my life (both mom and that used to be academics, and I spent 8 years in academia myself doing a phd and postdoc).
The amount of crap studies, politics and bullshit that happens in those circles will make you realise how sad the state of the "advancement of science" is. And my experience was in 3 very different countries. We desperately need something like AI to be able to synthesize and filter scientific publications