How many people that homeschool are actually knowledgeable enough and have the free time to replace full time teachers.
That said, having spent quite some time following families on the internet that have done this with their kids - including the Bucket List Family...
https://www.thebucketlistfamily.com/
and Logan LaPlante with his Hackschooling TED Talk...
https://www.youtube.com/watch?v=h11u3vtcpaY
To name just a couple of examples.
I have to say there are quite some advantages if it is done right, but not everyone is fortunate enough or has the background or passion to pursue this kind of schooling with their kids. It takes the kind of commitment that not many parents have.
And you wind up with a few kids that do really well and others that struggle with science and still others that just don't get the help they need with stuff. It is easy to overlook a learning disability at a young age when you aren't trained to look for it.
We don't even have a program to test parents on the material they are teaching. In a perfect world, parents would have to pass testing a level or two ahead of their lessons and we'd have more short, standardized tests to make sure kids were learning what they should (no skipping out on sex education or evolution, for example).
Short, meaning once or twice a month for 15-60 minutes, depending on a child's age in addition to something akin to finals for older students.
She was a part of some homeschooling group where the kids would get together frequently and the parents would takes turns leading different activities, often leveraging different parents' professions or special expertise. She was both well-socialized and had much more deep and engaging experiences than you can get in school.
Though you still end up with the problem of when and how to rejoin the normal world since you're so far ahead.