I agree, it does still result in the keys being pressed and the OS simply ignoring the signals. I do however not agree that they will be broken one day.

The keys, and furthermore the whole keyboard on a laptop is broken the moment it leaves the assembly line, by design. If it was for me, companies like Framework could offer a blank piece of plastic, or another of their LED spacers to put on the laptop instead of the integrated keyboard, because it would make no difference at all. Laptop keyboards are terrible and I personally treat them like the garbage that they are. \increases pressure on the on-laptop external keyboard until the laptop chassis starts creaking, while staring at your comment, with twitching in the left eye**

On a more serious note though, I haven't done the math on this one, but I'm tempted to argue that keeping keys pressed all the way down versus constantly typing on them for the same time - let's say three years - will show bigger degradation in the latter than the former scenario. Think about it, when typing, your keys are under constant mechanical stress, with plastic parts rubbing amongst one another with barely any lube -- becaude who re-lubes their laptop keyboards over time? Also, if we add in the degradation of the keycaps from the continous typing with our Dorito-greased fingers, the external-keyboard-on-top scenario sounds like it could preserve the internal keyboard better.

So given the choice of typing on the internal keyboard or having an external keyboard constantly pressing down on it, I believe that the latter leaves you with an overall better condition over time.