I've often wondered what the point is of someone keeping time with a baton or hand, when the orchestra is highly skilled and can understand the piece and the score to a very high standard. (I'm thinking in the context of major national symphony/philharmonic orchestras, where member expertise/quality/competence is not in doubt).
I understand that a conductor is also responsible for other functions, some of which are also expressed using the baton or other hand gestures:
interpreting the piece and how they want it played: this would seem to be the main or best-known function, but surely with competent players it gets explained and points covered during rehearsals. By the time of performance, the players know what's wanted in detail and will have annotated their scores for their parts. (If they don't, they won't get more info during the performance than they could at rehearsal.)
keeping time: the bare time keeping function itself seems something that a metronome could do, if it was needed at all. (I'm assuming a competent national player can keep time in a performance)
shading the piece for the audience mood, hall acoustics, and how people are on the day: wouldn't need baton style beats per se to do this?
providing communication between different groups that can't see or hear each other or whose perception would be distorted by location, line of sight, etc wouldn't need beats per se (or at least not continually)?
off-stage musical directorship: sponsors, pieces, terms, negotiations, organisation, membership. Non baton work.
So my question is whether the baton or hand's overt time-keeping role is essentially not much needed, and in reality it's just a vehicle for expressing other kinds of performance guidance. Alternatively, whether the orchestra does actually need a time-keeper as well as an expression-guider during a performance (so to speak).
Put another way, if a conductor could express stylistic guidance in a performance, and convey how they wanted the music expressed and parts played, in a way that wasn't also keeping time, would they be able to adequately do their role and would the orchestra be affected?