Gloomhaven 2e solo scenario masteries

I have seen in the FAQ that you can complete masteries during solo scenarios, does that not defeat the purpose? Some solo scenarios, like the cragheart one, literally do the mastery by themselves, with the scenario effects, or the mindthief one with how the enemies stand, even though in this one you need to do something at least lol So it seems kind of odd to me that you can count these...