It isn't so much replacement costs, it is that an unkempt desktop can cause actual physical hardware damage or degradation. A phone is a solid state device, whi

It isn't so much replacement costs, it is that an unkempt desktop can cause actual physical hardware damage or degradation. A phone is a solid state device, which (except in extraordinary circumstances) won't have bad ventilation problems. The variability in the state of the hardware you get is much wider in notebook and desktop hardware because there is just more circuitry to break and more moving parts to wear out.