But that's entirely different from replacing the battery itself with an expensive bench power supply. That can definitely work, especially if it's a high-end source/measure unit capable of being programmed to emulate the discharge curve of a real battery.
Every laptop I've ever owned will run with the battery disconnected.
Except the Macbook, of course.
The simple fact of the matter is that Apple routinely makes design decisions that are not only questionable, but compromise the usable life of the device in the process. And keep repeating the same mistakes over and over.
https://www.youtube.com/watch?v=AUaJ8pDlxi8
Having reduced or nonexistent performance after removing the battery was never normal. It's bad design. Period.
https://www.engadget.com/2008-11-22-macbook-and-macbookpro-s...
Sounds like an attempt to handwave away bad design principles.
Smaller devices like phones tend to be paired with downright tiny chargers, but modern smartphone SoCs can draw a lot of power in short bursts (cf. all the controversy about Apple trying to prevent brown-outs when operating the phone with a worn-out battery). Apple's laptops are usually paired with power bricks that roughly match the maximum sustained power draw of the laptop. Windows gaming laptops tend to ship with power bricks that are 2-3x larger than any Apple power brick.