If ICs spend only 20% of their time in coding then there must be in an unproductive team and company. Product owners and managers could easily move tickets and fill excels and notion pages asynchronously. I really don’t see any important reason for synchronous work other than something has caught fire live.

If I were to use the 80/20 rule here - at least for startups - I'd say it's the opposite. Only a very inefficient company would have 20% coding time.

I imagine the scales start turning the other way as companies grow, which is exactly why big companies move slowly.

What you're describing is work that is riddled with red-tape. Some of it might be necessary, but 80% is a bit too high.