They did burn all their rubbish yes (though I hadn’t heard of them burning new electronics! That’s crazy!). I was just highlighting the particularly nasty stuff, but there was also organic and even human waste burned.
Yes, there were so many unnecessary electronics that defense contractors convinced the Army they needed to bring to Afghanistan. Commanders never tied them in to their operating procedures so they went unused. When it came time to close the outpost shipping was not an option so EVERYTHING had to be burned.