I may just be thick but I still do not understand why you keep referring to the 'terminology of omniscience' as being 'unhelpful'.
Well, what I said was that I find it unhelpful. Clearly others find it helpful. I'm not telling them they shouldn't. But I suspect I am not the only one that finds it unhelpful, based on the many people that I have encountered who are left uncertain as to how they should handle it.
In what way is Omniscience in relation to a writing POV restrictive? The word by itself suggests nothing beyond the narrator having knowledge of everything about every character.
I'm not suggesting that is it restrictive. But in third person, at least, how could the reader tell that the narrator does not have knowledge of everything about every character. The certainly never tell everything about every character. They tell some things about some characters.
The real dividing line here seems to be character's thoughts. Either the narrator does not tell you the thoughts of any character, or they only ever tell you the thoughts of one character, or they tell you the thoughts of more than one character. Curiously, both the first and the last tend to get labeled omniscient POV, while the second gets labeled close POV. My suspicion is that the device of following only one character and giving their thoughts (in third person, as opposed to first, where it is entirely natural) was developed and needed a name, and that there then needed to be a name for everything else, and that got named omniscient.
And if anyone finds that distinction helpful, more power to them.
For anyone who, like me, does not find it helpful, I merely suggest that another way to look at the problem is to think in terms of whose voice the reader is listening to, because it seems to me that it is when the reader loses track of who they are listening too that they get disconcerted.
But these are merely mental props to help you through the complexities of composition, and you should use whichever ones work for you.
All decisions on how to convey the story are made by the writer -as they are in any POV choice. Comparison to making movies is not comparing like with like. Movies and writing are totally different mediums.
I'd be the first to agree that movies and books are not the same art. But they do both tell stories, and so there are similarities in storytelling that we can discern between the two. Much of what has been written on storytelling in the last hundred years has come from the movie side of things. (Show don't tell is a much more clear and obvious directive in the movies where your primary medium is pictures (which show) not words (which tell).) Movie directors soon learned that they could make a better movie by moving the camera around and mixing long shots with closeups. Novels have long enjoyed a similar freedom compared to plays (where changing the scene is expensive). So, yes, I think that the ability to frequently change point of view is a strength that novels share with movies, and the suggestion that in a novel you have to choose one POV and stick to it is highly limiting.
Maintain a consistent voice but change POV as required therefore seems to me a more helpful mantra than choose one POV and stick to it. But again, these ways of framing the craft are merely mental props. Use those that you personally find most helpful.