I have ruined several keyboards (3 Apple, 1 HP) by accidentally spilling water/coffee on them. What I don't understand is how do these devices get completely

I have ruined several keyboards (3 Apple, 1 HP) by accidentally spilling water/coffee on them. What I don't understand is how do these devices get completely destroyed by small amounts of liquid. I've disassembled these keyboards, cleaned and dried them out to no avail. Is something getting shorted out permanently ? Is some sensor getting ruined ? what exactly is happening and is there nothing that can be done to revive them.