DY: Every community is different. Every community has different types of interactions between different people. And yes, the Yetzer Hara is different depending on your lifestyle (e.g. the guy who went to public school has different Taavos than the Chassid who has never seen a woman before, just because of what they’re used to so things affect them differently). What this couple did is not abnormal in the Syrian (and Persian, honestly) communities and many do so while being entirely Shomer Mitzvos.
We can be Dan on that T’shuvah of R’ Moshe all day, but at the end it boils down to a psychological assumption that he makes (he says so explicitly). That assumption is probably not true in the communities under discussion here.