Yes, thank you @joecooldoo.
Gang, when something is in dev, it's because it's not finished! It's an experiment. The whole thing might be removed if it turns out to be way too slow. It may be completely redesigned. So it's really unhelpful for people to yell at us because it doesn't do everything you want. It doesn't (yet) do everything we want, either.
This is an adaptation of a piece of Smalltalk philosophy, namely, all of Smalltalk is implemented in Smalltalk itself. That's where Jens wants to get with Snap!. Right now, there are a lot of blocks implemented with that PRIMITIVE thing, but Jens has just begun work on what will be a big project! Over time, but before release, he'll try to get it down to maybe a dozen primitives. Or maybe zero primitives, but some lower-level primitives that aren't in the palette, e.g., I'm just making up this example, but the current primitive SET var TO val might be implemented in terms of SET var TO val IN ENVIRONMENT FRAME env, which would add or replace a binding in a particular frame. So the part of SET that searches the current environment to decide where to put a variable would be written in Snap!. (But then maybe in version 10.3 the creation and management of environment frames and environments would be implemented in Snap! too.)
TL;DR: This is a big deal; Jens is just beginning on it but is very excited about it; if you're excited too, don't rain on his parade.