Do we really know what "Live" music sounds like?

Kind of a bogus question. My music is different than yours so you can’t say music is only un-amplified. My music is all amplified and I have spent decades playing music in different bands, so I know what certain instruments should sound like.

99% of the concerts I attend are outside and quite a few of them you can hear the guitar thru the fender amp, others you hear everything from the PA system.

You bring up mics/pa systems, how about the room/hall/arena you hear the music in? That makes a huge contribution to the sound. 
I would take a concert in a great amphitheater that is amplified instead of an orchestra concert in a concrete building that is not built for good audio

Spent my entire childhood singing in groups and choirs un-amplified music. A choir doesn’t require application if the signers are taught correctly. Attended a church that only allowed un-amplified music (no instruments - voices only) performed by all the parishioners. I also spent time learning to play the guitar and the piano. I had to listen to a brother learn how to play the bagpipes.

I have a pretty good understanding what live "un-amplified" music sounds like. It sounds very different from music that is transmitted through a speaker.

Does a movie sound or look like a play, no.

Am I the only one that the only thing that really stuck with me from the article was how the author thinks it’s OK to go into a music store and lie to the workers and waste their time trying to improve the sound of the author’s system?

Most live music I have heard has sucked, especially rock music, utterly dreadful....big over blown booming bass...way way too loud....saw imagine dragons a few years back, sounded mostly awful. Marron 5 at the TD garden sounded a little better....However, the Boston symphony Holiday pops concert at Boston’s Symphony hall sounded fantastic. Ahhhh the good old days! Just a short two years ago! Insane....