Another old fart printer here, I believe I built my first kit printer ( a local guy's) back around 2011 after hanging out with the local group a couple years.
So yes not only do I remember wood filled, but I have used it. For best results ( to avoid clogging) i used a .8 nozzle. I program cnc's so modifying the program with temperature changes was easy. You could get woodgrain like effects. You just had to be careful not to burn it.
I also had "polywood" ever hear of that?
It had like micro glass bubbles i think? So it simulated wood by its feel. It was really fun stuff to play with. Made tons of fuzzy bear give aways. I wonder if polymaker still makes it?
David