Part of it is volume. You need 30-50 violins to get the same amount of sound that comes out of a single tuba. Part of it is tradition/history. Orchestral mus

Part of it is volume. You need 30-50 violins to get the same amount of sound that comes out of a single tuba. Part of it is tradition/history. Orchestral music is written with the assumption you’ll have a specific proportion of the various instruments, concert halls are constructed with acoustics that assume you’ll have the same proportions, etc. Nobody is going to stop you from having fewer violins in your orchestra, but to do that you’re going to have to take on work that other orchestras don’t have to take on.