We have pretty much the opposite logic and primarily use our pump and FW tank when we're out RVing, we always fill our FW tank at home with chlorinated city water as we have encountered poor quality water at many of the places we frequent.
I know many will say why carry the extra weight, we do it because we can, we often boondock anyway and don't want questionable water in our FW tanks, and not having to attach/detach hose and regulator makes set up and breakdown that much simpler.
We make the attempt to turn off water pump when leaving rig, unfortunately we don't always follow through, thankfully no issues in 3 decades of RVing. Heard all the horror stories, but being connected to constant hose pressure from spigot would make matters that much worse.