I've worked with people who thought parsers were straighforward and trying to fix the bugs in their code was fraught with impossibility - there can sometimes be

I've worked with people who thought parsers were straighforward and trying to fix the bugs in their code was fraught with impossibility - there can sometimes be millions of ways for parsers to accept invalid input or not accept valid input. In one case I gave up on fixing the code where every change introduced new possible bugs and used a parser generator. We never had another bug in that part of the code but my wholesale change caused intense friction. I feel that a course in parsers would have helped that person to understand this wasn't an appropriate situation. In fact I think it's a good idea to have BNF "that works" before you hand code anything just to confirm that you understand your own language design.