Not to insinuate that it's a great theory (none of the theories are really great), but I don't think it's all that bad. The premise is one I could get behind, provided that she is only ANOTHER incarnation of the Force, not specifically Anakin's reincarnated spirit.
Personally, I think the only possibilities that make sense at this point are that she is a Force incarnation, or that she is really just a random girl, as TLJ said. The theories about her being a Kenobi or (ugh) a Palpatine are reeeaaallly stretching things. However, to say that she is Luke's daughter, or Han and Leia's, is possibly even more egregious, as that implies that either Luke, Han, or Leia are incredibly awful parents, who willingly abandoned Rey on an inhospitable desert planet under the care of the smarmy lowlife Unkar Plutt. You'd think the characters we know and love would have at least tried to leave her on a more forgiving planet, or at least with a much more caring guardian.
Honestly, all this is why I think that--despite some of his poorer choices--Rian Johnson went with the best answer for Rey's parentage. The fans complained very vocally about how Luke was old, grumpy, and depressed in TLJ--I can't comprehend why they would want him to have abandoned his own daughter in such awful circumstances. Doesn't that make him less of a hero just as much as TLJ supposedly did?