There are way more parsers out there in production than the top-ten programming language implementations. Just think about serialization formats (json, bson, pr

There are way more parsers out there in production than the top-ten programming language implementations. Just think about serialization formats (json, bson, protobuff, et.al.): There are maybe 10 or so widely used. Then think about message formats (http, xml, yaml, ...): Maybe another 10 or so? Then think about configuration languages (.ini, .toml, ...), let's call that 5?. On top of that we have a bunch of widely used scripting languages (Make, sh, various lisps), I would say again 5 or so. So for any new language, say rust, you want (ideally) parsers for about 30 or more languages in real-world use cases. And that does not include language prototyping or consider the fact that recursive-descent parsers are usually not available as libraries (say for use in an editor). In conclusion: Having good automatic parser generators readily available is very relevant. And "good" can obviosly include usability, IMO.