I have heard that the reason for this is that trucks in that size range are less regulated by the EPA. Companies didn’t want to put in the research to develop trucks that met emissions standards, so they just make them really heavy for no purpose, evading regulations. Take this with a grain of salt, because I’ve done zero research of my own on it.
I recently learned that in my car the same light is used to indicate that the parking brake is on and that the brake fluid is low. Nothing bad happened, and it’s getting worked on, but my first thought was that the sensor on the brake must be broken. It’s poor design, seemingly without reason.