You're presuming that every phrase was worded _just so_. This could very well have been from the author refactoring their sentence and not simplifying everything. They probably were thinking in these terms (the author is a PL guy from MSR who's pretty heavy into a lot of the formalism) and this sounds like a not-perfectly-polished formal thought.
It's technical, and sometimes technical writing isn't written perfectly. That doesn't mean it's due to willful obtusity, or trying to sound smart.
It's technical, and sometimes technical writing isn't written perfectly. That doesn't mean it's due to willful obtusity, or trying to sound smart.