Chairs are given large safety margins, and designed to accommodate a wide range of people. Chips also have safety margins, but chips are not chairs, and there a

Chairs are given large safety margins, and designed to accommodate a wide range of people. Chips also have safety margins, but chips are not chairs, and there are other forces causing overpowered ARMs to be put into simple electronics, namely prevalence and mass production bringing the price down to pennies, so much so that it costs far less to develop some high level code for an cheap overpowered ARM chip than develop some more specialised embedded code for more "appropriately" sized microcontroller for the job. Sometimes things will still sway back to the specialised chips when things like power constraints or more specific hardware features carry enough weight for the purpose.