There’s actually a safety factor there. When Li-Ion (lithium-ion) batteries fail and suffer thermal runaway (fire), it’s most commonly during charging. It’s rare, but it does still happen. The rule is to avoid charging Li-Ion powered devices unattended. I do that at times myself, but I realize the risk and actually put things in a “charging pot” if unattended.

You don’t need anything fancy to use as a charging pot, a ceramic casserole dish will do. If you’re going to charge while asleep or out of the house it’s not a bad idea to use some kind of containment.