I have two (2) conflicting data points on this, but not using throwaway, rather VDB and authorized reroute. I suspect that this was a function of how the respective agents handled it.
Example 1: MUC-SFO (1-stop ORD). VDB on ORD-SFO, rebooked ORD-SMF, all miles posted MUC-ORD-SMF.
Example 2: STT-IAD (1-stop SJU). VDB on SJU-IAD, rebooked next day SJU-IAD. Got miles SJU-IAD, but never got miles STT-SJU.
So I think there's some merit behind what username is trying to say, in that the lack of presence on SFO-LAX may void the entire coupon (and the mileage posting entirely).