There have always been lots of ideas. The issue is the management consultants and finance took over.

I've never worked for an employer, from pizza delivery, to corporate intern, to multiple startup, to FAANG, that didn't have this VERY CLEARLY worded in the employment agreement, right up top:

1. Any work you do during company time/resources/equipment, is company property.

2. Anything public related to work, or that could be considered as competing or providing the service in the same space as work, needs to be vetted by the company.

Along with public communication, etc.

In my experience, this isn't some "what happens when MBA's run company" or "they run out of ideas", it's literally every company I've ever worked for.

Was google previously an exception here, or are people just unfamiliar with the details of the 20% policy? Surely they didn't allow you to work on, for example, something for a competitor? There had to be some limitations, rather than a pure free for all, as seems to be suggested in the comments.