I think you’re going a bit too far here. Only beer geeks (on beer forums) or those lucky enough to have been to Germany will really know the difference between a German Marzen and an American. But that really isn’t the point. Given that the market gets flooded with Oktoberfests every year, it should be apparent that the average beer drinking Joes don’t care if it’s “to style”. And frankly, they shouldn’t care. Style is pretty subjective and pointless anyway. They drink it not out of ignorance, but because they like it (or at least think they do!). And it doesn’t matter to them if you and I don’t.
If beer drinkers are complaining to a brewer who is brewing to style that the beer they are brewing is not Octoberfest, then yes, they are complaining out of ignorance. Sierra Nevada received quite a bit of negative feedback that last year's Octoberfest was not Octoberfest beer because it was not the sweet, caramelly mess that Americans have been led to believe is Märzen. Märzen is not an American beer style and Octoberfest is not an American event. Märzen is not even the primary beer style at Octoberfest and has not been for a long time. That is why the beer served today is called festbier. Acting out of a lack of knowledge is the very definition of ignorance. We have to remember that American's thought that North American Industrial Lager (NAIL) was how beer was supposed to taste for a long time. A lot of Americans did not like the taste, so they did not drink beer, that is, until craft beers started to show up on shelves. Heck, I was primarily a wine and spirits drinker when I drank before I started to brew because I was not a fan of most NAILs.
I started to brew in the early nineties when American Märzen came into style. I am partly with Jeffy. The style is the result of using imported beer that was past its prime as a reference (Vienna suffered a somewhat similar fate via its association with Mexican brewers). However, it is also due to ignorance about ingredients, which in large part was due to lack of access to high quality ingredients. The North American brewing economy was radically different in the early 90s than it is today. The major industrial brewers controlled everything. The microbrewers, as they were called at the time, received what the industrial brewers did not want and the home brewing supply chain received what the microbrewers did not want. The first decent imported continental malt did not show up until the mid-nineties and when it did, it showed up in 50kg/110lbs bags. The maltster was DeWolf-Cosyns. George Fix pimped the heck out of that malt, but it was still 50% more expensive in bulk than domestic 2-row.
Most of the breweries, and I will use the word "brewery" loosely here, that brewed micro lager during the early days did so on the East Coast as the West Coast was busy with with American ale creations. The reason why I used the word brewery loosely here is that most of the micros that were producing lager were little more than labels at that point in time. Beer production was primarily handled by regional industrial lager breweries under contract. Samuel Adams was one the major players in the contract brewing world. Their early beer was brewed at the Pittsburgh Brewery Company, which was home to Iron City industrial lager. Other contract lagers were brewed by F.X. Matt such as New Amsterdam and Olde Heurich. F.X. Matt's main beer was its Saranac industrial lager. Contract brewing breathed new life into regional industrial brewers who were fighting for their very existence due to consolidation. Hence, all of the beers that would establish the American Märzen style were formulated with malts commonly available to NAIL brewers, which were a far cry from the malts that were available to German and continental brewers. Jim Koch made a sales pitch about how his beer was all-malt and used imported Mittelfrüh and Tettnanger hops, but the reality is that North American brewers already used these hops, albeit in smaller quantities, because they were part of the North American industrial lager brewing supply chain. Almost all of the work performed by Al Haunold and his predecessors at USDA ARS Corvallis, Oregon was in an effort to replace the imported noble hops with "like" hops that had better agronomics when grown in the United States. All of that research was in large part funded by the large industrial brewers, mainly Anheuser-Busch. Anheuser-Busch eventually built Elk Mountain Farms in Bonner's Ferry, Idaho near the Canadian border in order to obtain a peak photo period that was long enough to successfully grow landrace noble hops. Heck, even Willamette research was funded by Anheuser-Busch because they used Fuggle to finish Budweiser.