Which is how you should write SQL in my opinion (and many others) it makes it much clearer and easier to understand.

The other advantage it makes bugs where you use a Reserved word where you should not much easier to see visually

Pretty much this - hence my upvote for you.

I also like to stylistically indent my SQL to make it easier to follow. This works well for most typically use cases, but it can fail horribly when you start to certain kinds of JOINs and such - the indenting will make things more difficult to read.

Of course, once you start doing really wild things with SQL, no amount of casing or indentation will save you.

Indeed, this is a common workaround when your editor has no proper syntax highlighting. Still, in today's world nobody would write in that style in other programming languages.

You see the same issue with other relicts, for example, Pascal back in the 90s. Old text books wrote Pascal in uppercase style:

  PROGRAM HelloWorld(output);
  BEGIN
     ...
  END.

But in reality, everybody using e.g. the Turbo Pascal IDE wrote lowercase instead, because it easier to type and because of proper syntax highlighting:

  program HelloWorld(output);
  begin
     ...
  end.

Maybe this is not so much about the maturity of the developers (as I assumed in the previous comment), but about the maturity of the tooling.

Had a purpose. Now we have syntax highlighting.