Poplar is considered junk wood? This is news to me. I’ve seen plenty of poplar furniture.
It's often used as trim that's painted over, as many don't consider the wood pretty. I love seeing poplar with a wide variety of colors.
It’s brittle, light and flimsy. It has its uses but is not great for furnitures or burning.
It’s too soft to be of much use except the odd piece of furniture (for which it is pretty terrible because it dents too easily). As a woodworker finishing it also sucks because the fibers tear too easily. Its grain pattern looks bland at best, it ages poorly, and its color is too inconsistent from tree to tree.
That said, it’s one of the most stable woods so it doesn’t warp much which is why it’s a popular base material for plywood and it’s easy on cutting tools. I usually only use it for the interior parts of drawers.