When people ask questions like "Why does it take X engineers to run twitter?", well that is the reason.
If this was already the case at your company before the WFH, then yes, WFH didn't change anything, or even maybe let your emloyees work on the wrong thing even faster.
The other thing people don't appreciate is that it's significantly harder to find good managers than good individual contributers. I believe that management is about 300% more efficient in an in-person environment. As in, I can effectively make sure that 3x the number of people are working on the correct things in an in-office environment.
I find it nearly impossible to find people with the ability to do this correctly right now, let alone somehow needing to find 3x this number.
Even if people worked at half speed at the office (which I don't really believe), that is still worthwhile.