I think you are romanticizing the situation Mia. Though great question.
Your question seems to me the following: Here are a bunch of people sitting and speaking and each one sees their tiny viewpoint by what interests them. You ask if this narrowness is needed for an artistic life?

My answer would be that this is not restricted to artists and is common to most people. People see their own world-view everywhere, and care about their own current problems. Some more so, some less so. It's how people are, but there is no reason to idealize/glamorize it.

In fact, in the continuation of the cafe scene, which doesn't appear in the short clip (it's outside your frame), there is a different message on how people communicate and absorb other people's suggestions. Owen Wilson gives a suggestion of a movie to Bunuel. The suggestion seems ludicrous but he is in fact describing Bunuel's The Exterminating Angel. So even though they each look from their own tiny point of view ("I see a film," "I see a photograph") something passes, gets communicated and absorbed. It's a nice miracle.


As an aside, Dali it appears had an obsession with the rhinoceros, especially their horns, for example painting this funny version of Vermeer's The Lacemaker with rhino horns:

   

Hey Chris,
that's a beautiful painting you quote. I especially like how the focal point of her fingers and the needles remains...

I am almost certainly romanticizing, it's such a marvelous scene! But it's a problem even Dali acknowledges in the clip: loving France, but the waiters not so much. The general idea of singularity is almost certainly more interesting than specific narrowmindedness...

With Dali and the rhinocerous though: it's almost like the ancient idea of a totem animal, something which is very far from us these days. Naturally, I would connect it to the discussion on the monstrous, though rhinos are not monsters -- they're animals, which is certainly different.

Moreover, they are, it should be pointed out, animals with a very specific tool distinct from the rest of their body -- this magnificent horn -- which is really of a different material than the rest of the animal, and which the animal uses to interface with the world. It's like a sword, or a paintbrush, getting between the animal and everything else. You can certainly see how an artist might be viscerally drawn to this. 

Must artists narrow themselves to live an artistic life?
It seems to me that the answer would be both a yes and no.

Certainly the act of producing a work of art requires a focus, a narrowing down, toward an exactness of expression. To the degree that the artist expresses an exact communication, in a way that others can understand or feel the intent, to that degree the piece has reached its audience.

Even a feeling of 'vagueness' can be communicated, but, the art would not lie in an unintended vagueness. The art would lie in the intentional creation and communication of vagueness.

On the other hand, great art, art that survives and communicates well across the ages, requires of the artist a deep understanding of broad encompassing elements of life. Styles come and go, but an artist who understands/feels grandly, and commands their art, will produce great art - Art with a capital "A".

Put another way, small minds produce small thoughts. Great artists must be broad in understanding and feeling, but focus to the exactness of the 'thought' (s) they want to communicate.

How they choose to live their lives is another matter. Dedication to their art in relation to other aspects of their lives, and/or, focus on a particular subject or theme may have been the 'gist' of your question. My focus narrowed to the quality of the artist's understandings and communication. Communication always narrows. In saying this, we exclude that.