> But reading some of the made-up syntax in the "Removing Coherence" section makes my head hurt.

Articles discussions new features always have difficult syntax. There have been proposals like this going on from the start.

Fortunately the language team is cognizant of the syntax and usability issues with proposals. There have been a lot of proposals that started off as very unwieldy syntax but were iterated for years until becoming more ergonomic.

I think it's more than the syntax, it's just the number of concepts you need to keep in your head to read a type signature, or a trait declaration, or whatever. There's only so much you can pack into a limited language before it becomes too much to keep in your head at once.