What are the bare necessities of making a movie?
My films have varied wildly - 'The Artefact' had myself (I was also acting in some scenes) and one other person, that person changing on a daily basis. It was halfway through my first year at uni, none of us really knew what we were doing, we pointed a single light at whatever we were shooting, propped the boom up on a chair and sat back behind the camera. Amazingly this system worked.
Jump to my latest film five years later which had a relatively full and well organised crew and it didn't work quite so well. In this regard I'm not sure what's genuinely necessary ina film crew. Personally I'd like to keep it tight and get a close friendly family-like unit who are all as dedicated to a project as each other. I've not doubt you can get that on a larger crew but I've worked on sets where there are more people sat around waiting than there ae actually doing anything and I don't get it.
This comes back a little to my gripes about how much big films cost as excessive crew seems an issue, but let's not get into that. To be fair I tend to micromanage like an irritating control freak anyway so I'm possibly not a great example, but for the purposes of the relatively tiny films I make as long as I've got a DoP and at least one person for every major role (sound, lighting, fight choreographer, whoevers needed) and maybe two or three "jack of all trades" people to fill in the gaps then that's enough isn't it?