Well the way laptops and anything else generally works is that the power goes to the battery, which then provides power to the device, in case something is unplugged.
That puts constant, but not deadly wear on the battery.
So if the laptop will be plugged in for a while its a good idea to remove the battery so it wont be used at all.
but with sealed batteries, you can't do that.
I don't really know what to recommend though in that case? maybe using it down a bit and then plugging it in? Itd be nice if there was a switch to bypass the battery entirely, but that wont be the most practical.