When trying to find differences between virgin and recycled scap plastic all I get is AI crap product comparison sites and various companies trying to sell their recycling system...

What downsides is there to recycling your own plastic scrap, which you have had full control over the entire time. I would imagine trying to color match with consumer waste plastic is a nightmare, same with moisture (at least that's an issue when printing). But if you have a bunch of plastic in an homogeneous color and you grind it up to make something of the same color, and you've had the scraps in a controlled environment, then what more issues are there?