Every computer is just space heater with side effect of computations.
The same way every diesel engine is just oil stove with side effect of rotary motion. If the engine was in the back of the car you could totally put a pot on it and braise something.
A diesel engine is a very inefficient stove though, as only half (more or less, depending on the exact engine) of the energy is converted to heat, the leftover being mechanical energy.