What’s this increase in fragile adults you’re talking about? Are you sure it’s a real thing? Are you aware how staggeringly high rates of institutionalisation were in most western countries in the early to mid 20th century? And then there were the adults who were considered ‘sickly’. Like, _fainting_ wasn’t considered dramatically abnormal behaviour until quite recently.

A lot of people who today would be considered to have a condition which is entirely treatable by doing (a), taking (b), not doing/avoiding (c), etc, would, a century ago, have just been kind of deemed broken. Coeliac disease is a particularly obvious example; it was known that there was _something_ wrong with coeliacs, but they were generally just filed under the 'sickly' label, lived badly and died young.

(And it generally just gets worse the further you go back; in many parts of the world vitamin deficiency diseases were just _normal_ til the 20th century, say).