I think that is false, there is more artisanal furniture today. In the past people had less furniture and most of it was junk. With power tools people can afford more good furniture, even though it is lost among all the junk. Don't forget that good furniture lasts longer than junk and what the past made is kept for decades.

Also with the much larger population today, a small percentage of craftsmen still dwarfs the output of the past.