A big reason I use MPV is because of anime. I forget exactly what the reason was back in the day, but I can remember MPV being better at playing certain formats, and fan subs of anime are early adopters of new codecs. In addition, there is a very healthy ecosystem of plugins related to language learning, which again ties back to anime.
I honestly had given up hope this would ever happen. For global menu enjoyers, this is the holy grail of programs that just refused to play nice.