I think MJW was just talking about regional differences and how some people don't understand/keep in mind/lose track of and in some cases simply ignore.
I don't know who the Dennis he's referring to is or what he said about drip edge but I do know "being from Ohio myself" that in my area of Ohio drip edge doe's not play as important a role in the roofing system as it doe's in other areas, it's purpose is actually as much for aesthetics as for mechanics "in my area".
So if this Dennis guy made a comment stating drip edge to be unimportant period, than he was obviously ignoring/not thinking about/not understanding of regional differences.
I see it happen in this forum and others almost daily.
Example: 3-tab shingles are junk and roofers who install them are below par roofers.
Yet in my area I can show you 20 too 25 year old 3-tabs still intact on roofs with no missing tabs or leaks and I can do so with out leaving the city block I live on and if we did leave the block I would end up showing you thousands of squares of 3-tabs that met or exceeded the 20yr & 25yr &30yr life expectancy.
Materials and workmanship both differ from region too region.
I can always count on you to provide a cut and dry perspective Slyfox.