Rhonda Kinahan wrote:
that was 2015 and maybe something has changed since then.
The first Apple support document about fonts I can find was for macOS Sierra in 2016: Fonts included with macOS Sierra - Apple Support. I just happen to have a whole bunch of virtual machines for testing my app. I can check the progression of fonts since 10.9
OS version: Total number of font files (Number in read-only /System/Library + Number in read-write /Library)
2013, 10.9 - Mavericks: 275 (43 + 230)
2014, 10.10 - Yosemite: 282 (48 + 232)
2015, 10.11 - El Capitan: 305 (89 + 214)
2016, 10.12 - Sierra: 284 (102 + 180)
2017, 10.13 - High Sierra: 296 (114 + 180)
2018, 10.14 - Mojave: 309 (127 + 180)
2019, 10.15 - Catalina: 334 (333 + 1)
2020, 11.0 - Big Sur: 446 (356 + 90)
And here it is in a graph:

As you can see, there has been a steady increase in the overall number of fonts. There has also been a steady shift in fonts from the 3rd party /Library folder into the Apple-controlled /System folder.
Catalina had a major change to the security model, isolating the operating system into its own partition for added security. Big Sur introduced the new San Francisco font and stored it in /Library. The San Francisco font has special technological features for retina displays and user interface design on both iOS and macOS. It is designed to be used only in apps. Its licensing enforces this. Perhaps the big font shift in Catalina was in preparation for the introduction of San Francisco.
But all of this is specifically talking about files on disk. Apple has a long-standing policy that what developers may or may not find in the filesystem is not an "API". Apple only supports official programmer APIs. If a programmer makes use of the fact that a file happens to be in a particular location, they are taking a risk. Apple can move those files around at any time. As the chart above clearly shows, they actually do that.
Apple provides official font APIs. These are provided so that all apps on the system can handle fonts in the same way. If you organize your fonts a particular way using Font Book, you should be able to use that same set of favourites in other apps. That's the whole point of APIs. Otherwise, every app would be doing it differently. I used those APIs in my little demo app. The language metadata API was added in MacOS X Tiger 10.4 in 2005. The font collection API was added in MacOS X Lion 10.7 in 2011. These interfaces are over a decade old. Apple has done this before.
I remember when Apple deprecated an old, insecure networking protocol many years ago. "Deprecation" means that they announce to developers that they are going to discontinue some API. It is a warning that any developers who use that API need to switch to a newer alternative. So Apple announced that an old, insecure AFP network protocol would no longer be supported. Then, 9 years later, Apple disabled it. Every 3rd party NAS (Network Attached Storage) device in the world broke on that day. It seemed that 3rd party developers simply ignored Apple's communications until it broke their products. Then they blamed Apple, as did their customers. I remember it well. There was another incident too, with a 9 year delay. I can't remember the details of the other one. Remember, we are talking decades here. The years get confused in my old brain after a few of those. And now we have fonts, with almost the same 9 year timeframe.
Your point of being able to create a piece of code sounds simple for you in your skill set. The majority of us cannot speak that sort of language. You illustrated a potential solution with proprietary code, however simple it was for you but not so much for me. It seems reasonable for Adobe to listen to this idea.
My code is not proprietary. It is open source.
Adobe has 21,000 employees. You will have to ask Adobe why none of those developers could find 9 minutes out of just one day, over the span of 9 years, to make this fix.