>>39128800Several reasons.
She's usually very busy with recording and Hololive work nearly everyday, with songs and other stuff, both at home and at the offices + the usual idol reps.
Also, Mio has a fragile health and tends to get motion sickness easily. Those kinds of puzzle/strategy games are usually alright for a few hours alright but action games are much harder for her (and FPSs are straight up making her sick) so insane endurance streams like the other girls are doing are pretty difficult for her.
It's been like that since debut, the very vast majority of her streams are 1-2 hours long, and it's also part of the reason why she stopped reading Superchats early on.
Another thing, she really wants to take care of her throat and keep a healthy lifestyle: Cooking properly, taking some time for herself to relax, not going to bed too late
at least, she's trying and all that stuff...
And the most important reason:
Someone has to take care of the cats. 