Yes, I do not know how working in the office = healthier. Have some of these people that make this argument been to an office before? Group lunches are always "Lets go to McDonalds/Wendys/BurgerKing/whatever". I have severely limited my "bad for your health" lunches since working from home. Making my own sandwiches and things.
Not everyone is the same. Yes, some people have 5 kids, 4 dogs and 3 cats that impact their work. But not everyone is like this. I am single, have no pets, have a dedicated office to cut down on distractions. My productivity shot through the roof working from home. You think productivity will INCREASE when people get back to the office? It will take a nose dive especially at the start "Hey Tom, been a while since we saw each other huh, nice beard!" - then talking for 10+ minutes. Then someone else stops Tom for another 10 minutes. Working from home, if I am busy with something and someone sends me a Slack message, I can ignore it for a few minutes until I finish my thought. Instead of being "stopped in the hall" and lose my train of thought.