Knotty softwoods can make perfectly suitable furniture. They can (and are) grown at scale.

I’m sympathetic to the viewpoint that the supply particleboard furniture has suffocated the marketplaces for mid- and low-end wooden furniture. Such pieces definitely exist affordably (I’ve bought them at places like Marshall’s, for instance). But they seem comparatively underrepresented in the market.

Maybe a consumer preference for flatpack furniture is enough to explain this? But then again, wooden furniture can be flatpacked too—ikea has plenty of it.