A lack of density closer to cities is a real problem: it makes living close to where you work prohibitively expensive, and promotes sprawl.
Of course, part of the subtext of these discussions is that proponents of SFZ and owner-occupancy tend also to believe that their favorite cities should have controlled population growth. It's just not a good look to say that out loud.
That's one cause. The other cause that you seem to refuse to understand is creating the wrong kind of density. An urban centre full of 1 bedroom apartments is still going to create urban sprawl because families just can't live there, thus driving them out of the city centre even though they still work there. I just don't get why you refuse to understand this very obvious point.