Some of the points raised about level of heat involved got me thinking. I'm not so sure the idea of getting deep into the grooves makes sense giving that uses fine nylon brushes and lots of fluid should get in there pretty well.
I think the heat is killing bacteria and removing mold that otherwise remains when using cool/cold fluids. But who knows...
I keep thinking about a bit I heard on the news or science class about hot water on you face and skin and how it takes very little heat to open up human pores; the point was that you don't need scalding hot water, in conjunction with soap, to get clean. but I think it helps that we have "hot" vapor involved here of course.
I'm thinking about a simple pre-cleaning with steam and was looking the mini Joy Mangano units for about $5-10