They kinda are necessary, given how they're the byproduct of capitalism's private property model and its commodification.

You could technically remove them by having the state manage all the housing, but that's overly idealistic given how that'd go against the ruling class interests which would cause heavy lobbying by big landowners. It would also make the state a monopoly landowner which would have its own implications.

In other words, they're necessary not because they're useful, but because of how dogshit the system is.