It does also work for them that they retain employees who are more likely to put up with their bullshit. They can cull the truly lazy ones at a later date as required, either by firing them or finding a similarly bullshit change that they’re likely to be adverse to.
Money.
Also I imagine the ads will be silent but animated, like a regular website ad but full screen, essentially turning whatever you’re watching it on into a giant billboard.
It’s just another thing to block I guess.