Engineering resource is finite, the less time spent on working on the engine the more time we can spend working on new features and other systems.

Before making this in Rust we experimented with a Go and also a Lua implementation as we investigated the approach. The Rust code took the same time to initially produce and was production ready very early and has been rock solid and required virtually no maintenance since it was put into production.

That frees up that engineer to work on other things, whilst also reducing ongoing maintenance that was anticipated and so those engineers are also working on other stuff.

I'd attribute a chunk of that to Rust... though it helps if you have great engineers who are familiar with the concepts of parsers, etc working on these things. The same may not be true if someone new to Rust was also new to the concepts needed.