On the other hand, a coffee percolator is not a young person's device,
only people who drank their coffee before Mr. Coffee, Melita filters,
and Starbucks would even think of using one. I'm sure there are a lot of
older people out there who would buy one but have never quite grasped
the concept of no metal in a micro. :-)

Actually, modern microwaves are more tolerant. You can put a metal tray in a
microwave, and nothing bad will happen.

The issue isn't metal, per se -- a metal plate reflects microwaves as the
cavity walls do -- but sharp spots at which the field intensity is so high
that you get corona discharge or arcing.

I once put a jar of Adam's peanut butter in the microwave to warm it -- and
you should have seen the arcing at the tiny -- really tiny -- bits of
aluminum that were left on the lip from the seal.