There are people building with the underlying stuff already (holesail/liveport for example, my brother's peardrive project, & there are a bunch of other things that could be built very quickly). There are modules that connect the back end to the front end stuff which are not finalized yet. If everyone starts building with code that will be changed, then the entire ecosystem breaks. It's the same reason there are so many constraints around linux kernel development & bitcoin development. But they have opened the parts that make the connections. When you use it or build with it, it is pretty obvious that it all works as described. And the front end stuff is still clunky.