[KennyBlanken]

And if you screw up which battery is which?

"Do things exactly right, quickly, or the device bursts into flames*" is not acceptable electronics design, even for something you intend to use yourself.

* do you really want to trust a generic battery's built-in protection IC?

[Forgeties79]

Maybe I’m being too generous but I feel like 99.9% of the people using something like this would do it properly

[II2II]

Now that I'm aware, sure. If I wasn't told, I would assume that they were designed so that a new battery could be swapped in while one battery remained inserted to maintain power (much like an old Thinkpad I used to own).

[Nab443]

.. until their curious child decides to have a look at it.