Ok if you really want to know... maybe it's because:
(i) just being expected to play root notes with the occasional 5th thrown in, gives us the headspace to think about other things, like gear, and to spend hours discussing it on Bass Gearchat?
(ii) if someone else did it instead of us, the rest of the band would almost certainly find a better bass player who had the time to put into practising (instead of doing the damn PA, lights, bookings and promo), and
(iii) the likely end result is that no-one in the band would have any gigs to play at!
...now can we get back to discussing DMX please? 😅