Don't roll your own parser? How the hell would you get anything done? Unless you don't count regular expressions or something, I can't imagine somehow avoiding problems requiring parsers, especially on any unix-based system.
There are a lot of tasks that only need to work with existing, commonplace file formats with existing high-quality parsers (e.g., JSON, XML, sqlite, ...).
SQLite I can grant you, but I'm starting to get a bit worried about certain XML parser popular in C/C++ land. Might do a swing at it with a profiler later today.
This is a sign that writing (trivial) parsers is a core competency for you. However, that doesn't meant that writing all parsers is your core competency. Especially not for an industry standard like JSON that should have plenty of libraries that take care of the problem.
