Good point, additionally, how do you expect the relationship to grow if you are not unable to unfortunately secure basic private lodging?
Most women might be fine with this arrangement while casually dating in younger years but I have yet to see anyone being at ease in this situation.
Don't forget that we are talking about 30+ years old, at this age most people are looking for something stable, of course you can always find exceptions but your available pool of candidates shrinks.
Oh, I fully agree that people ok with this arrangement beyond 30 years are rare. But if that’s who a person is, why should they give it up? They should keep searching for the soulmate that is also ok with this arrangement.
This type of shared apartments also have the effect of creating a sort of microcosm of people thinking alike on this specific topic. You tend to get to know other such shared apartments. This changes drastically the odds of finding partner ok with this arrangement.
Source: I lived 5 years in different such shared apartments, the microcosm effect really was insane, I automatically got to know the friends of my roommates, half of whom lived in a shared apartment, then I got to know their roommates, etc. 3 of my relationships started because of this network.