Apple hasn't sold a "line" of monitors since 2010. Just a singular one (other than overlap when a newer model came out). The latest one wasn't exactly a great seller either... If you fit it's niche it was a great display a few years ago... today... meh. It also had no OSD, can't speak to the revisions before it on that though. As such, it makes sense for them to get out of the business of selling their own (singular) display.
I'm seeing nothing non-standard whatsoever about this display. As another comment mentions, it's using DCC/CI, it's using a standard thunderbolt 3 connector. So are you suggesting Apple is charging too much for it? I'm not sure I can even buy that as there's not exactly another 5k resolution wide gamut display out that I've seen yet.