As for Akka, well Akka is really not about abstracting over I/O or a replacement for Netty, even though projects like akka-http exist. At this point Netty is so good, well tested and so widely deployed that nobody sane would even dream of replacing it, even though there are some people trying.
And on the .NET ecosystem, I really love what Microsoft is doing with it and how .NET Core is turning out, however open-source is definitely a big weakness of the ecosystem. In the Java world, Oracle is not driving anything other than Java the language and the runtime (i.e. the core). Not the IDE, not the frameworks or the tools being used. Everything else is provided by the community.
And when I click to view the source of some class or method in my IDE, I have my IDE automatically download the original source, instead of getting a decompiled one, because proprietary libraries are almost unheard of.