My personal experience with laptop batteries was not as nice as yours, but neither should be blindly trusted.

Not sure if there is some science on it anywhere but this random search result article pcmag.com/…/help-my-laptop-battery-is-swollen-now… says:

most common cause of a swollen battery is overcharging. Keeping your battery at a high state of charge can stress it out, allowing it to degrade faster. “In an application where you have a system plugged in 24/7, after a number of years your likelihood of getting a swollen battery increases,” says Phil Jakes, principal engineer and director of strategic technology at Lenovo. “The other thing that drives it is heat. Batteries don’t like to be hot, and there’s a chemical process that gets kicked off when a battery gets over 100 degrees.”

So I guess best is to set charge limit and make sure the “server” doesn’t get hot.