It isn’t so much a matter of skill really. Just, there’s a random probability that any electronic device will catch fire because the manufacturer cheaper out on some component. If you’ve screwed around with the internals, it takes it from the “obviously not my fault” scenario to “there is an argument to be had.” Being right but having to argue with your insurance company anyway is still a pain, right?

> Funny how there is always someone who posts "you do X, and you will fail" ...

That is not what the post to which you replied said nor implied. Instead, it reads thusly:

  Dishwasher electronics are subject to elevated heat and 
  humidity levels. A DIY solution will be extremely 
  unreliable. An amateurish job on the power electronics can 
  be a fire hazard and will void any insurance policy if they 
  find out what you did.

This is clearly a warning to those reading this thread. Likely also an attempted knowledge sharing with the post's author.

> Maybe someone who is skillful enough to be able to DIY a micro-controller will also think about these issues and deal with them too?

Maybe all people who attempt such things are not aware of the concerns raised?

Need more Doug Jacksons (SV Seeker) in this world.

Safety third.

99% of people who played with an Arduino in school are not EEs and are woefully unqualified to be doing that sort of tinkering for a hardwired appliance managing high voltages, water valves, and heating elements that can all cause mayhem when a self-taught Dunning-Krugerian steps out of their wheelhouse.