There's always a fascinating range of opinions and preferences. I have no doubt that someone out there prefers a mono mix. Probably with an Academy filter on it. Perhaps we could digitally simulate the nonlinearity of a variable density optical track and take that the rest of the way.
The industry professionals and soundtrack creators would disagree, and probably not be real happy about their meticulously crafted 5.1 track being reproduced in anything less. So the solution there is, don't invite them over.
Those with strong opinions, once fully polarized, will take no notice of any technical reasoning as to why other channels or speaker types might offer an experience closer to the creative environment. Nothing can be gain, for example, in pointing out that the vast majority of content in any soundtrack is contained in the center channel, for which 2.1 doesn't even have a speaker. No matter, though, if the 2.1 owner is happy (not being sarcastic this time).
Define your goals, do what it takes to get as close as you can to them with whatever speaker number and types it takes. Building up a system that lets you hear it all in the way it was created will be a very different goal from building a system with the fewest speakers possible and hearing a remix of every track. Nothing wrong with either, if that's the end goal.
You are all "right" in your own world, perhaps not so much in someone elses.