you're lucky you're running into models that don't panic in some way without a battery.
for example some alienware and XPS models rely on the battery for amperage capacitance when their big onboard GPUs get busy; allows them to run cooler/less-wattage/smaller wall-warts but it also makes for a platform that'll crash when it hits a high GPU usage without a decent way to make up the amps.
'spose you could use a bigger power supply if you get bios/uefi to play nice. hard proposition sometimes with Dell products.
Well, of course I'm not getting old gaming/pro laptops with dedicated gpus, they would consume far too much power, require extensive cooling, and these are way too expensive anyway, even when broken. I usually get old, boring office laptops (lenovo/dell) from bulk resellers, with integrated graphics who are sufficiently used/broken so they are dirt cheap. As long as they still turn on, the mainboard is usually fine (I've yet to get a broken one).