Interesting!
That's quite contrary to my experience, granted I've only used two magic mice, one for 2 years in 2014-16, and another from 2020-2023.
It's possible that your experience is much more common though!
Right there that's my experience as well.
I doubt the Magic Mouse defenders use their computer all that much or even use a Magic Mouse at all.
That thing charges annoyingly slowly and uses battery way faster than reasonable.
It's probably just Apple's usual arrogance. They could have easily designed the mouse so that you can keep using it while it's charging, but the designer chose otherwise. And because this is a minor enough issue, Apple doesn't have to fix it and admit that they were wrong.