Hydraulic system loading
A few times I've seen quips about avoiding using multiple hydraulic systems (like gear and flap movement) simultaneously, because of the extra wear and tear the increased load can put on the system. But this doesn't make sense to me, and I'd like to make sense of it, or confirm that it's bunk. With other types of systems I can see the issue. With electrical, we have increased current and heat flowing through the components. With mechanical systems, we get closer to the yield limits, increased chance of fatigue cracks, etc. With an engine, the implications of loading it more are obvious.
But with hydraulics, we have have fluid, pushed by a pump, staying at a regulated pressure, and running through actuators. With multiple systems using it simultaneously, of course it takes more flow to get the job done (and maybe the pressure would decrease), but there's no more pressure or stress on the lines or actuators. As for the pumps, if anything I see this easing their load as they're pumping against less resistance.
Maybe I'm looking at this simplistically, but what am I missing?