Because video off meetings are entirely pointless and just shouldn't be run. Not to say that turning video on magically makes the meetings have point, but if you are muted, video off, and doing the dishes, you just shouldn't be in that call.
Requiring video on probably makes people push back against being invited to useless meetings rather than seeing it as an hour to clean the house.
People that schedule meetings like that don't want pushback. They're not trying to optimise the list of people in the meeting, they're trying to grow it at the expense of everything else.
They genuinely believe that whatever they're crapping on about to a brick wall for 2 hours straight is the most important thing in the universe and they want your undivided attention, productivity or profit be damned. That's why they force people to turn their cameras on.
You don't always have an option and when you do there are consequences. It cost me my grades in high school (during the lockdown, in an European country) because I was adamant on not wanting to show myself on camera. The same thing happened when looking for a job. I'd rather face the consequences rather than give in.
As an individual you may as well do dishes, but as a company you should believe that your meetings are actually important, and if they are, everyone should be present and video on. At least that way there will be pushback against useless meetings.