This argument has not kept up with the reality of the public school system. The homeschooled cohort my children are associated with have problems associating with public school children of the same age... but the problem doesn't lie on the homeschooler's side, it lies 100% on the publicly-schooled children's side! The public school attendees are noticeably less mature for the same age and less able to deal with anything other than the highly-specific and unrealistic environment of public schools rather than the rest of the world. The homeschoolers have trouble stepping down their social expectations to levels the public school attendees can meet.
We have a few reasons unrelated to socialization [1] to do home schooling but one of the reasons I don't want to send them back is precisely the regression in "socialization" I would expect.
30 years ago, this probably was a decent argument, but the bar of "at least as socialized as a public school attendee" has gone way down in the meantime.
[1]: I guess before anyone asks, one of my children is deaf-blind and while the people in the system did their best and I have not much criticism of the people, the reality is still that I was able to more precisely accommodate that child than the system was able to. This ends up being a pretty big stopper for a return to the public school system for that child.