This is a strange assertion. This is not envoy, it's haproxy as you've always known it plus all the features people have been asking for recently, without removing what makes it fast, robust, compact and flexible. From what I've seen you can't for example use dynamic weights in envoy, protect from DDoS, perform queuing to protect your servers, use true leastconn or weighted hash/roundrobin, stick on arbitrary information nor synchronize it between members of the cluster, create complex routing rules, set the source address from headers, perform transparent proxing, etc.
These are two different projects. One was initially designed for the hostile edge and excels here. The other one was initially designed to be used as a side car deep into your infrastructure and excels there. There is obviously quite some overlap between the two, sometimes with different terminology (like "circuit breaking" in envoy that haproxy calls "timeouts" and "queue limits"), and users demands make each of them evolve a bit in the area they are less good (i.e. where the other one excels). But they are still quite different beasts.
These are two different projects. One was initially designed for the hostile edge and excels here. The other one was initially designed to be used as a side car deep into your infrastructure and excels there. There is obviously quite some overlap between the two, sometimes with different terminology (like "circuit breaking" in envoy that haproxy calls "timeouts" and "queue limits"), and users demands make each of them evolve a bit in the area they are less good (i.e. where the other one excels). But they are still quite different beasts.