After COVID many school districts in the US that weren't offering online only school are now. Suddenly they had the capacity to do it as it was forced on them with COVID, so maintain it for students who want it is as easy as anything else.
It makes it hard for them to adjust fast.
The purpose built school from home programs are often far better run / budgeted IT wise. I was at my son's high school and the school from home kids were there for an in person day borrowing the lab for some in person time / activities and etc.
If there's enough of such students in a district's boundaries, I think it makes sense to accomidate them within the district, rather than push them out. It will allow easier movement to/from a classroom setting, and feels more likely to provide continuity than a 3rd party offering. Then again, school districts cut things all the time.