It's never, ever wise to automatically agree anything.
I recall making that comment in response to an apparent assumption that all Betta are in-bred and, as such, lesser fish in all respects. To anyone who believes that, then non-inbred fish are available, although poor care would hasten their demise just as well.
As to them needing bigger volumes, I'd suspect that most, if not all, would benefit from having larger volumes to inhabit...wild-caught AND farm-bred.
Whilst it is true that in the wild, these fish may only have a relatively small territory that they call home, they've actually been able to explore their environment and choose that home for themselves. Because they've actually chosen it themselves, they're more likely to thrive in it.
This concept shouldn't be confined to wild-caught fish either.
A friend of mine specialised in Betta and he had huge tanks for them. He taught me that whilst the farm-bred fish had only been used to cramped conditions, many of them flourished when given room to move around. Some really did remain relatively static for the remainder of their lives and these didn't live as long as those which regained some of their more natural behaviours.