Thermal runaway protection does not help in certain failure modes.

Failed FET for instance. They tend to fail "on". Unless you have a highside FET shutting off the power (and that may fail too).

On my printer I have software watchdogs but I also have an entire "dumb" (no MCU) circuit that will shut off a large relay that goes to my heaters if any of it's failsafes are triggered. I have a smoke detector, secondary thermistors, etc.

There are a bit more things in the way of thermal fuses and heaters that are less likely to runaway on the newer commercial printers but I still think people need to take the risk more serious.

I have been building printers and printing since 2011 and I still prefer to not have my printer in my house where the family sleeps, even with the failsafes. It lives out in the shop with plenty of room around/above it in case of a fire.