it's not that simple. it's because things are medium bad conductors, like the nichrome wire in the toaster, which is absolutely fantastic for setting things on fire

things that are really good conductors like the copper wires in the toaster don't heat up (much) because they don't drop much voltage, and things that are really bad conductors, like the panels that support the nichrome wires and like calcium carbonate, don't heat up at all, because they don't carry any current. it's the things that are in between that cause fires: they can carry enough current to be a problem, while also dropping enough voltage to be a problem

this has been introductory electrical engineering 101. i'll be here all week, don't forget to tip your server, and read chapters 1 of horowitz & hill by monday

that's partially true; however, I still think I was right.

yes, there are places that don't heat up because the current doesn't go through them, but only because they have easier paths. if the electricity wanted to go through them, they would heat up hotter than anything else.

the point is, things can corrode, electricity goes in places it wasn't intended or through resistances it wasn't intended, and becomes a fire hazard.