I’m referring to when someone in the band, or the choreographer or whoever, counts to start things off. Why not just start with one and go from there? Achieves the same thing with the added bonus of being logical, right?
“2, 3, 4” is the final three beats of a lead-in…the vast majority of music in some genres, particular jazz/pop/rock/band stuff, is based around four beats. Counting in all four isn’t necessary, just the last two or three are needed to indicate the speed and feel of the music. Counting ‘1, 2, 3’ for these beats would be both confusing and wrong. And in dance in particular, larger groupings of these fours into eights and sixteens are important, hence the ‘6, 7, 8’ lead-in.
Good answer. A better(?) one is that specific beats have specific names. The 2nd, 3rd, and 4th beats of the measure are named 2, 3, and 4, respectively. To name them 1, 2 and 3 is not only not logical, but downright confusing. It would be like saying that Bill Clinton’s first term was served in the years 0001, 0002, 0003, and 0004.