All the nintendo games for mobile have a monetization system in place.
They have monetization in mobile games, sell dlc for their games, re release games multiple times, keep rehashing the same old franchises over and over again, they have have lootboxes to some extent, they merchandise the living hell out of their properties, they make fairly useless peripherals all the time, etc. Even amiibos are borderline microtransactions but because I get a cool figure I can forgive it.
Nintendo basically does everything people hate about other companies but they don't get called out for it because they have soft and friendly games like mario and a smiling non threatening Japanese man who is very pleasant representing them. Granted they aren't as invasive as some other companies but they still do it.