From what I gather in the GitHub repository, they implement their own L7 management, instead of using NGINX, Envoy, HAProxy, etc. IMO, this adds quite a bit of development cost with minimum benefit.

Kong has built on OpenResty (which is built on NGINX), Ambassador has been built on Envoy Proxy -- I think these projects will be able to sustain their velocity more so than projects that need to maintain their own L7 engine. Just watching the speed at which Envoy Proxy is adding stuff is kind of staggering; hard to imagine how another company could do the same on their own homegrown engine.