I agree and there used to be (maybe it's still the case) problems with parser generators if you wanted to have good error recovery and reporting to the user. It's also very telling that sometimes--contrary to what people might expect--parsers pose a substantial problem in production systems: http://cacm.acm.org/magazines/2010/2/69354-a-few-billion-lin...:

Law: You can't check code you can't parse. Checking code deeply requires understanding the code's semantics. The most basic requirement is that you parse it. Parsing is considered a solved problem. Unfortunately, this view is naïve, rooted in the widely believed myth that programming languages exist.