No one is "stuck" or "resorting" to anything. It's an effort to improve tooling, performance, error reporting, and working with Ruby in general. We could maintain the status quo (which does indeed work) or we could improve it. If we don't improve the status quo, people call the language stagnant and outdated. If we do, it's considered a criticism of its maturity.
How many languages would even entertain such a contribution? How many languages are so tightly bound to their parser that writing a new one wouldn't even be workable? How many languages have user tooling that works extensively with parsed code snippets? How many languages have multiple implementations? Of those, how many are working together on an effort to share a common parser?
There's plenty of valid reasons to use something other than Ruby. An open source project that grew organically over 25 years deciding that it's time to pay down some technical debt and improve the ecosystem at the same time is probably not one of them.
How many languages would even entertain such a contribution? How many languages are so tightly bound to their parser that writing a new one wouldn't even be workable? How many languages have user tooling that works extensively with parsed code snippets? How many languages have multiple implementations? Of those, how many are working together on an effort to share a common parser?
There's plenty of valid reasons to use something other than Ruby. An open source project that grew organically over 25 years deciding that it's time to pay down some technical debt and improve the ecosystem at the same time is probably not one of them.