It's not improving the parser, it's improving the language's syntax definition, which shouldn't care about this in the first place.

PHP's parser is the language syntax definition. It's perfectly reasonable for any PHP developer to attempt that call because it should work. PHP's parser, for no good reason, just doesn't like it. I'd consider it a bug rather than design problem.

Without having investigated it, I would guess that the parser isn't abstract and modular enough so they end up with a mess of code trying to handle all the different possible combinations of syntax.