Dishwashers get _quite_ hot for a long period of time, and there's relatively harsh chemicals in there too. Does anything realistically survive that anyway?
Even desinfection does not kill everything.
Also no need to, bacteri and virus are a normal thing. The problem is, if too many of the wrong type get in your system. So reducing them in general (and also normal washing machines do that) is mostly sufficient.
(And dishwashers indeed kill microscopic life with heat and chemicals, but that is a side effect of cleaning)