Let’s start with:
1. Big streams are not only fandom result but also non fans aka GP. For example: SEVENTEEN have a bigger fandom than TWICE but the GP support is hugely different from each other, that’s why TWICE streams are so much bigger than SVT.
2. Fandoms that only care about buying albums and do not stream or care about it. I see that trend a lot in boygroup stans with the “They have big album sales they don’t need streams” or the famous “Album sales brings more money” which is true but brings more money to who? Most of the time to the label not to your faves.