Chiming in here. I moved across the country to SoCal and returned to the company I left, (re)-starting in Sept. 2019 as full-time WFH. I worked 4-5 days in the office before the move.

I'm a good control here because I've worked for the same company:

1. In the office

2. WFH pre-Covid

3. WFH during-Covid

What's more, all of my favorite activities: golf, hiking, cooking--are largely unaffected by the pandemic. My income's been the same and the work activities have been roughly similar.

I felt relatively productive WFH pre-Covid but something has changed that's affected my productivity/motivation--and I can't put my finger on it. I think it's the general, subconscious, back-of-my-mind feeling that things are profoundly going to shit that's dragging me down. It's been a struggle now when it's not been before.

This is all purely anecdotal, but I think I'm a good case-in-point example of your position: that WFH is a convenient strawman to hand-wave away the effects of people living in the final pages of a Vonnegut novel.

I love WFH; I want to be productive; but I don't think that shoe-horning people back into offices (wearing a mask all day, nonetheless) is going to magically turn everyone back into creative, chipper good-time-charlies.