Leaving the main power breaker on
I can't remember if it was our orientation when picking up our 2017 Sprinter from SMB-W, or somewhere in the owner's manual, but at some point I "learned" that it's best for all the AC breakers to remain off until needed. But I didn't learn why, beyond some horror stories of flipping the "H2O Heater" breaker on and accidentally running the Espar water heater from the house battery.
Anyways, our breaker panel is awkward to reach, in the back of the cargo compartment accessible only from the outside and typically blocked by various gear. So I'm wondering if there's really any risk or battery drain leaving the main breaker and the breakers for the relevant AC outlets on, and just turn the inverter on and off whenever I need to charge the laptop, whether parked or driving.
My theory is that flipping the breaker off is absolutely the right thing to do before connecting or disconnecting shore power, since that'll create spikes and surges, and that's where the general advice to always keep it off comes from. But if I'm getting all my power from solar and the alternator, is there really any downside to leaving the main breaker on all the time?