Totally agree. Li ion batteries are great in a flashlight, never leave them floating charge.
They do fail, and it is because of overheating during charge or discharge cycle.
But if one shorts in the bank there is no way for the system to know which cell is causing it. Disaster.
Yes, which is why I only charge the big battery for my Stihl Hedge trimmer or chainsaw in my garage. I also never leave it plugged in at night.
That way there is at least 5/8 firecode Type X drywall between my house and the garage.
My wife has a suitcase that has a built in battery to charge her phone. Anytime we travel on a plane the gate agent makes sure she takes that battery out of the suitcase.
This is also why they want everyone to pull their laptop out of their carry on bags. To make sure your laptop does not feel hot because your battery is overheating.