Iv'e seen the negative effects of WFH with my own eyes. Is it anecdotal? yes. Is the positive impacts anecdotal? also yes. Will people be biased to what is comfortable in the here and now? the exercise is left to the reader.
No. Lack of commute is concrete and tangible. Even just from an emissions standpoint.
Decreased spending on office space is not anecdotal, but again concrete.
Reduced office costs are real. You would have to pay more per employee just for the office costs alone.
This then demands concrete proof that productivity is higher in office -- which has never been provided.
All of these have material impact on productivity, but more importantly healthy and happiness of employees themselves. The effects are not uniform, but there are tradeoffs and it's not clear to me that wfh is better for everyone.