>>38765
If we want to untangle this we have to check what type of woods they use for making furniture?
1. "full" wood
2. recycled wastage, maybe they ground/mince/crush pieces of normal wood to make more splinters, shavings, chaff, maybe not, but I can imagine they do that.
From the wastage they make slabs with some binding material and/or press, or whatever. These, no matter what type (plywood and OSB are two types but when I have the time I'm gonna make a little research) they all sag by themselves if they placed wrong, so doing it purpose is child's play.
From full wood they rarely make furniture anymore. Maybe chairs, and table legs, but if a furniture is full wood, it is most likely custom made for rich people, or built by a hobbyist for himself, and the cost doesn't really matter.

Next question should be what parts of a furniture have to be curved? Usually the sheet that covers the backside. That - in quite a few instances - is just a thin piece of flexible slab which can be bent on demand.

Actually even some normal lumber can bend by itself if placed wrong, like pine boards/planks.