I am very late to this thread, and it's a good thing as I don't really have a stake or opinion in any of this.
However, I did want to give a bit of insight on one thing that came up quite a bit in this thread.
The subject of standards in the recording/mastering side of producing music.
I am a musician, and studio engineer, and acoustics engineer and have spent a lifetime in and around studios. For many years there certainly was no standard way of producing and mastering audio. As you know, recordings are all over the map when it comes to balance of frequencies, especially bass.
However, in recent years, that has and continues to change. It's not so much that a published "standard" like the Harman curve exists, it's more like a move to a defacto standard based on a few things that are pretty consistent and based on similar methods to Harman.
What's happening is two fold. First, studio engineers are relying more and more on visual tools when mixing and mastering. The visual tools all show the balance of frequencies and there is a pretty consistent approach as to what is "good." Many products even show a "standard" curve to match your mix to, albeit a bit different depending on the genre of music.
The other piece that is also doing a similar thing is "automated mastering." There are many places now that offer what amounts to AI mastering, Landr bein the first big one, but now there are many more. Likewise, most of the mastering suites that are being used in DAWs also have a way of analyzing and coming up with a master. In that world, all of these things are taken as a
starting point for your mastering and not necessarily the final product.
However, Like all these things, they started out pretty bad. You would submit your material and then spend a lot of time tweaking it to be what you wanted as an engineer or producer. But as time has progressed, these tools are getting very good. To the point that many times what the software spits out is very difficult to improve upon, even among the best of mastering engineers.
I know a number of mastering engineers who have moved solely to ATMOS mixing and mastering, saying there is no way they can compete with the new tools that do it automatically.
This is moving the industry more and more toward an accepted "curve" for most music. Which as an artists, I'm all in favor of. I've known too many great songs by great musicians that never saw the light of day because the mix or the mastering was poorly done. I want to get past that and enjoy the great music.