You just happen to be conflating hard limitations of a physical substance with arbitrary soft limitations. Of course you cant replace chips with sand despite both having a % of silicon. Those are entirely different things.
Wine and gasoline aren't the same thing at all, they just happen to have one common element in their composition.
The iPad and a computer ARE the same thing. The label is something the brand puts on, it is not an hard limitation of the universe.
I personally don't care if IKEA says that their bedroom furniture is for the bedroom. If I decide to use it as living room furniture I can and IKEA should not have a say, however they probably would if they could.
Brands like to have that weird control when they can, generally not in worries we're doing something weird with stuff but for some strategic benefit, such as not cannibalising sales of something else.
If IKEA could bind pieces of furniture to types of room, you'd be more likely to have to buy more furniture over your lifetime. It would also maybe prevent them from having to comply with some regulation with the "our furniture is not furniture, is an... habitational support"! argument.