Can't the casual observer simply read those answers though and see that there are lots of great ways to solve this in Julia?

I agree that subclassing is sometimes nice to have. But I also think all langauge design is based on sensible tradeoffs.

Not adding it makes the language a lot simpler and makes other things possible which you cannot do in languages based on subclassing.

In every language I find things I miss from some other language I use. But based on my C++ experience a resitance the urge to whish for kitchen sink approach, where whatever language I currently use should support whatever feature I miss.

Less is more. Anyway can add language features. Good design requries being able to remove as much as possible without making the language impractical to use.

I miss things like operator overloading when I use Go, but would I want to add it to Go? Nope, because it detracts from the core design principles Go was built on.

Anyway, it might be that this limit of Julia makes it impossible or very impractical to use for your kinds of problems. But that is hard to know since I don't know anything about the kind of software you are trying to write. Maybe if you have the time, you could write an aritcle about it at some point.