To be honest, I think a lot of the 'fringe' benefits or disbenefits of boarding / not boarding are absolutely not the point.
Nor do they carry very much weight in the 'to board or not to board' balance whch parents who consider boarding have to do [as I say, I was a boarder, and am very aware of the particulars of the balance made in my case].
The main point, it seems to me, fior the vast majority of boarder is that boarding allows those parents who can afford it [directly or through bursaries / scholarships] to access a school which they cannot access each day. The benfits of that school - whether it be academic excellence, a specialist education, a 'British' education for those abroad or a removal from more local schools for a variety of reasons - outweigh, for those families, the disbenefit of separation.
Supporters of boarding don't NEED to claim any extra benefits of boarding - I have never heard a boarding family say 'it's to make them independent' or 'it helps them to manage money' or 'they meet more people frm different cultures, even thougyh they are far away from their 'home' culture'. If they truly believe that the benefit of being able to access that school is worth it, that is the point.
In a smaller number of cases, it is more pragmatic - what the school provides is a more stable childcare / place of residence scenario than is available for that particular child. My own personal circle includes families whose children board because parental employment is a series of 1 and 2 ear postings all over the world, or single parents with exceptionally long hours jobs who feel boarding school is preferable to a long series of au pairs. But again, the key reasons for choosing boarding are not those tussled over in this thread.
As I say, my parents chose for me to board for the 'majority' reason - an education not available within day travelling disance. DH's chose boarding for the second reason, of jobs all over the world. I genuinely don't think parents say 'oh, i'd send him / her to a day school, but I send them boarding for the independence'.