For one, it's anything but easy to write a fast and correct routing engine that produces good results. OSRM was (mainly) written by Dennis Luxen who literally h

For one, it's anything but easy to write a fast and correct routing engine that produces good results. OSRM was (mainly) written by Dennis Luxen who literally has a PhD in route planning. Secondly, if these projects already exist and are easy to integrate, I fail to see why it should be problematic for OSM to use them. OSRM is completely open source, anyone can spin up their own instance if they wanted to, so someone else can host it if the current server goes down. Open source routing engines like OSRM exist so that OSM doesn't need to roll their own. I'm having a hard time wrapping my head around how you construe this to be a bad thing.