Please don't misinterpret in this way. This is a candid reaction. As you indicate, it confirms your previous observations. This is not an opinion of you or any other Rust developer. It is an opinion of the syntax, period.
Though, you may also be referring to the "made up language" powered by the Macros. I agree that can be a bit much, but it's in my view no more distracting than React's JSX. Some people hate JSX, and I imagine they would hate this as well.
I use an ErgoDox, and while my layout isn't customized for writing mox invocations, it hadn't occurred to me that this might be a blind spot in my thinking about ergonomics. Good point!
_ is "don't complain because I don't use this variable"
|| is the syntax around Rust closures
foo! is a Rust macro
Why this is desirable is that we can program in real Rust while using some simple macro expansion not to create a free standing language for gui building?
Learning Rust via this gui library might not be the best choice(?) and I think it's better he focus on people that know Rust already.
Rust does have plenty of symbols (nearly all of which are lifted directly from C or C++, with the same or analogous meanings), but such extensive DSLs are rarely encountered in the course of everyday use of the language.
The important thing is actual expressiveness. Rust gives you a heavy duty toolbox to play with. You could have a beautiful-looking syntax with no braces, no parens, and tons of whitespace (think CoffeeScript or Haskell) where you're very restricted on a small set of square pegs, or you could use something like C++, (Perl), Rust, or Lisp that lets you make any Rube Goldberg machinery you want no matter how hideous it looks. It's a matter of personal preference. You can be very effective either way, but I think one is unnecessarily harder on yourself.
There are two camps:
1. Syntax is important. I want everything to line up beautifully on the screen. I have a riced out Arch desktop and a super clean enviable desk with modern furniture.
2. Syntax doesn't matter. I format code sloppily and let clang-format fix it eventually. I love macros and codegen because they make my life easier. I haven't changed my wallpaper in 5 years.