While I don’t disagree, in a sense this vipassana/samatha debate is just a matter of definition, though. There are practices in the suttas which are aimed towards abandoning the hindrances (the “calming” practices) and there are practices that are primarily aimed towards generating insight. It’s clear that you don’t have to do these things at the same time. For deep insight you surely don’t, that’s why samadhi is said to lead to seeing things as they are. The two are not the same thing; otherwise everybody who attained jhanas would be stream winners, and that’s not the case. You can attain the jhanas and get no real insight at all.
And while satipatthana is mainly meant to abandon the hindrances, there’s also such a thing as satipatthanabhavana in the suttas, which is said to be done after the mind is unified, it’s aimed at penetrating the dhamma deeply, to generate insight.
Now some people call the calming practices ‘samatha’ and the insight-focused practices ‘vipassana’. That terminology is not completely in line with the suttas, but that doesn’t disprove the general idea of these practices. It just shows they use terms differently.
(And what some people call ‘vipassana’, like scanning the body, is not really an insight practice at all, in my opinion. But once you realize that, then the actual method is not wrong per se. Just a different word is used.)
Sometimes people jump on inconsistent terminology (I’m not saying you are, but this is a general thing) thinking they thereby disprove the entire idea. It’s the same with some terms like “neighborhood (or access) samadhi” or what have you. Sure, the Buddha never used those words, but it’s the commentaries’ job to comment on things, and you can only do that usefully if you talk about things in a different way, using different terms. So if somebody uses “neighborhood samadhi” that doesn’t automatically mean their teachings aren’t in line with the Buddha’s. They just use different terminology.
And to be honest, I don’t know any teacher who is completely in line with the suttas with their use of terminology.
In short, it’s just too easy to say “oh this term is different from how the Buddha used it” and then conclude the whole system is wrong. (Again, I’m not saying anybody here is. I’m talking in general. You probably read some of these kinds of arguments in books.)
Just thought I’d say that. It may avoid some unnecessary arguments one day, or at least I can hope.