Nope. actual unschooling is good. Some don't do it correctly and those are the ones usually heard of. There are studies later than the one you provided showing it works, will provide links in a bit.
Edit: However, the paper and the citations from the link you provided says there is a dearth of uschooled and unschooling people willing to participate in such studies.
clearly not true. there's a student there asking questions!
...he feeds his school-work to ChatGPT.