So I’m genuinely wondering if there’s a corresponding exit from the workplace or other demographic trends allowing/pushing this boom in home schooling to happen?
Most of the adults you see at the various group things are stay-at-home moms. Most. Some stay-at-home dads. Some of the moms have part-time jobs. I don’t recall any dads with part-time jobs. But many dads are present while also working full-time. You get into a rhythm, have a schedule, etc. and you can work it out. My wife is fairly unusual in that she runs her own full-time business. Many moms don’t like her, presumably because they gave up their careers to do this and are jealous that she does both.
FWIW, my experience is that the dynamic at play in these situations is that women who run their own businesses or otherwise have high-powered careers tend to have a constellation of personality traits that is significantly shifted vs. those of stay at home moms, plus their daily lives are very different, so they don't really fit in. Saying that without value judgement, just an observation.