I think it's less about typing them and more about reading them. Curly braces reduce the number of keywords in the language (unless the alternative is indentation sensitivity like in Python or Haskell). This means that if I see a word, it is easier to infer if it is a variable name or if it does something structural.

How about a treesitter-based editor extension that converts between begin/end and {/}, as if they were ligatures? Actually this might not even need treesitter.