My quest started with wanting to know if it is ok to keep phone plugged in. I've read https://www.quora.com/Is-it-true-that-using-your-smartphone-while-charging-it-destroy-your-battery-power-over-the-long-term and https://www.quora.com/What-happens-if-we-charge-our-mobile-continuously-for-a-week and there most people tell it is good for battery because phone just draws power from USB / charger (only some power hungry use battery power in addition to charger). However, only some phones can be used without a battery https://www.quora.com/How-do-I-use-a-smartphone-directly-without-a-battery. It is a problem for some dissussed here: Building a circuit to replicate a LiPo battery
I have several phones (one ~5 years old, other ~4 years old) with removable batteries and they do not work without battery. I have several laptops - all work without battery.
I recall laptops used battery to work even when plugged in, but it was many (like ~20) years ago. If as claimed by answers in Quora smartphones draw power from charger to work, why many phones do not work without batteries?