There's also the novelty factor to consider.
Being able to play these massive, AAA open world experiences on a handheld is still a relatively new and therefore novel thing. I reckon this was a major reason why Skyrim on Switch was such a big deal.
I mean, imagine if, back in 2015 when Witcher 3 launched, you predicted that in 4 years we'd be playing in on a handheld. Most people wouldn't have even taken you seriously. Yet here we are.