What you said plays a smaller part than you think, as well. Data collection is a core part of companies like Tencent’s business model, but they can get that in more subversive ways than always-on DRM. And do.
This, however, plays a huge role. I’d say up to 30% of the reason for always-on DRM is advertisement.
Protection from pirates is a notable part of the system, and not worth laughing at given how effective it’s been on that front. The largest reason for the model, however, is control. Of the game and of play. It allows Blizzard to hotfix things, which is a seriously massive driving factor for developers opting for always-online. This is just the pleasant side of things, however. Control also spreads to other things, but I’ll let your imagination run wild with the negative effects of constant control of an online game. There are examples out there of egregious misuse.