I have no idea where this comes from. I've been working for a company that primarily puts me on long-term consulting contracts, which has me working for many different customers. Obviously, this needs to largely be remote, as I'm not going to move to a different city every year to accommodate some new customer's headquarters, but thanks to the last few years, most of these teams have been fully-remote teams anyway, and they have all been partially remote if not fully.
Other than the initial intro meeting, not only do I never have my camera on, but neither does anyone else usually. Meetings typically have three flavors. One, a periodic "standup" type meeting that involves going over an issue board. Two, an engineering peer review of some sort, that will involve going over a diagram or piece of code or a functionality demo. Three, some sort of swarm or pair programming type thing where you're either collaborating on creating something or troubleshooting an issue. In all of those cases, in order to actually do what you're trying to accomplish with the meeting, somebody needs to be screensharing.
But if there's a screen we should all be focusing on anyway, what would be the point of also adding N superfluous video streams to get distracted by?
Add to that the fact that, at least early in the pandemic, my ISP seemed to throttle me if I went over some unwritten weekly data usage cap I was a lot more likely to hit if I was adding in 8-15 HD video streams instead of just one.
This is different for very small free-form discussion meetings where a limited group of people is trying to reach a decision without having something to present. Maybe in that case seeing each other is warranted and helpful, but that is a very small subset of meetings. I don't see how it can possibly ever be justified to require cameras on all the time in all meetings.