I'm not a developer, so I don't know the actual effort involves, but it seems to me like making a new one is like reinventing the wheel. Matrix probably has solved many problems that this new things still has to run into.
What's an SDK? I looked it up but can't really understand the techno lingo on wikipedia. It's a "kit" (whatever that means) that allows developing a platform specific app? Matrix isn't another OS like Linux, so I'm confused.