I have seen a lot of people in my area assert that my political will should be subordinate to theirs because I came from somewhere else. Last place I lived, the notion that a particular demographic I fall into should be kept out of the general housing market when possible due to pricing others out was not just a fringe idea but part of several (ultimately successful) city council candidates' platforms. Perhaps people in your area are less nutty about outsiders.

If someone can't afford to live in some area…

Yes, those who can't afford the rent can live elsewhere, so rent control is not needed.