That doesn't mean that media that uses it should just throw it all out the window as "Lol, non-canon" and do whatever they like with the IP - that's not what is being said here.
Sorry, I wish your interpretation were true, but until WotC explicitly says so my interpretation is exactly what you say it is not, which is: A user/game developer can and should just throw all the lore from previous editions out the window as non-canon and do whatever they like with the IP -- so long as some snot-nosed kid at WotC who neither knows nor cares about D&D/FR checks off on it.
