No, that's not true, and it's that fantasy which gets us the "butts-in-seats" management style.
This is correlated first to workplace morale and second to the individual worker. The workers who would do this from home are the same workers who would do it in the office. And employers who make their workers' lives miserable will have endemic problems with people not putting in effort.
You joke, I assume. My boss was notoriously against working from home. COVID proved him VERY wrong. People where just as effective, if not more. They where much more flexible with customer. It doesn't matter that a client ask you to say a bit longer, if you're already home and have everything set up.
Most people I know never worked 5 days a week. They just pretended. Now they don't have to pretend as much (as long as that little Slack dot stays green!)
The ones in the office do the same. They just spread the day of not-working over the whole week and have the added stress of having to pretend to work some of the time.
Though actually it's more like 2-3 days of not working, spread out, more often than not.