[achierius]

This still isn't quite correct. Back in the day parsing was a much larger portion of the complexity of a compiler: performance was much more of a concern, as was memory usage. Parser generators were an attempt at helping with that, by allowing programmers to produce more efficient (e.g. table-driven) parsers than what they could have otherwise written by hand. They only really went out of fashion because A) computers got faster and bigger faster than programs got longer, so parsing became less and less of a percentage of total utilization, and B) you can get much better error messages out of recursive-descent parsers.