If I'm at an in-person meeting of 5-8 people, and 3 of them get into a longer discussion about things that are irrelevant to me, and for understanding which I don't have the background, I can zone out and nobody cares, because nobody is looking at me. Everyone is looking at the people talking.

On a video call, my zoned-out face will make the trio feel uneasy; instead of discussing their topic quickly, they'll stumble and try to "talk to the audience", or god forbid, drag everyone else into the discussion. So with forced camera on, I have to look focused while squinting at the other screen, discretely playing 2048 and pinching myself to not yawn visibly, while with camera off, I could get off my chair, stretch a little, or do something actually useful for the company.

I'll be happier with having always-on camera on long videocalls when videocalls start working like real-life meetings: not everyone is looking at everyone else all the time, and everyone can tell who's looking at them in any given moment. The way things are today, I find this constant surveillance to be mentally tormenting, and only activate my camera on the basis of courtesy: 1:1 meetings, some team meetings, meetings with an important higher-up who also has their camera on, etc.