Malabo,
what you say is correct..... unless you leave the bird parked in an deep African hangar with monkey helicopter engineers unable to count from 1 to 10 on their two hands junking around and playing pretending they're real engineers....or you work in extreme cold weather like Aosta or Sondrio in wintertime at 3000 meters, or you fly chewed asses in short range hems flying 10 minutes long missions, or you forced to shut down the bird for any reason on a drill ship only to discover the ship GPU is U/S in spite of what the HLL was stating before leaving base onshore (damned offshore operations!).
Also, maybe some of us do not have any copilot because we fly single pilot since the very beginning on type and even so the company check list wisely states if is battery or GPU start as a reminder and as the RFM says the same anyways; it goes without saying that we still don't need any checklist for start up as we do it routinely by heart.
Apart of personal recollections, there are quite some situations where we may be forced to start up bellow 23V without APU unless we love to wait for help on a mountain peak or into a remote jungle.
But mostly, this procedure is designed to avoid hot-starts after flying short legs without carrying APU and no time for the generators to recharge hard used batteries, you know that battery Voltage could be OK but battery Capacity could be not.
Cheers