Etching prime is not old school
The problem is in its misuse and true purpose.
Etching primer was designed for painting smooth metal that has not been mechanically etched with sandblasting or sanding.
The primer has some acid that will bite with the metal.
Lots of guys use it cause it is cheaper and all their buddies tell em to use it. Many people fail to do the most important step. Read all of the tech sheets and understand what each product is good for.
Epoxy is great but it must be applied to etched (chemically or mechanically) metal.
Keep in mind epoxy is not the only product that can be put direct to metal. A lot of the filling urethane primers can go DTM to. Just remember it is not good to put bondo type products over etching primer.
Go to your dealer and get a bunch of product sheets, read them, and go back and ask questions. Also ask questions at the paint manufacturers websites too. They have been very responsive to my questions and I tell them I am a hobbiest.