Why haven't custom parsers become more of a thing? All the compiler or interpreter really needs is a valid parse tree. You could even have some kind of special command or directive to switch styles, if a section would be really ugly otherwise.

With indentation-based languages the bad coding style we are talking about is putting multiple statements on a line or unindenting a block …& never has that been something I wanted to do. I would rather this aspect be enforced at the language for readability where there is still room in all other aspects to try out other styles.