This reminds me of growing up as a homeschooled kid and hearing people ask my parents "but how will they socialize?", generally while we were at the youth soccer field or at the playground or somewhere else that the irony should have caught their attention.
Homeschooled kids can be isolated more because they don't have the forcing function of mandatory group settings, but often there are other opportunities available for socialization beyond just the one normally-compulsory (and, often miserable) environment.
Similarly, remote work for the last near-decade for me has given me a lot more time to be engaged socially with my family and other local communities – time that used to be entirely lost to a long commute. My mental health is drastically better than when I was working in-office, largely because I don't have over an hour of traffic each way to deal with, and especially because I get to be engaged with my family more and be much closer and more involved with my kid than I would otherwise.
Homeschooled people just assume others must be unhappy in those places where they dont go, but that is not the case and not shown in statistics.
Also, those people asking the question you find weird were asking about the experiences and kind of socialization that they consider big deal and was not going on in that place.
I wasn’t homeschooled but I have been working from home for good part of last two decades. And I have not felt any negative effects of it.
In fact, it forced me to go out seek friends in local communities like meetups and various clubs. I have a feeling that people who feel isolated due to WFH would be same people who don’t interact with anyone in the offices as well.