Why is this not the solution?

[Jojoya]

Apartments were specifically for anyone who could not get a house.

SE made of point of saying when apartments were added that house owners could also purchase them, countering your belief. If they were only intended for players who couldn't get a house, SE would have blocked house owners from buying them just as we cannot purchase a house with an alt any longer if another character on the same account/world already owns a house.

I think apartments were primarily intended to be a cheap alternative to houses for players who didn't want to spend millions to get a house, and those who wanted to be able to take breaks from the game without losing their housing.