At least, until you start to define functions, whereby a line now says "something happens according to a definition elsewhere which is just invoked here".
Oh wait, that's also what a piece of syntax or macro also says, pretty much.
> I hope you can see the UI advantage to functional programming in an environment of controlled evaluation complexity
What I do know is that big programs written in C can be pretty difficult to understand, even though most of their bulk hardly uses much more than what's covered by the operator precedence table on page 53 of Kernighan and Ritchie, 2nd ed. A lot of that has to do with the fact that foo_bar(ptr_widget, 42, gadget_struct) can mean anything whatsoever, even though it isn't a special operator or macro call. The small assurance that three word-sized chunks are passed somewhere by value doesn't actually buy a whole lot of understanding.
(Brain* * * * * * has a nice, small, inextensible set of operators. Does it help?)
The dictionary you have to comprehend is not that of the language, but of the language, plus that of the code base written in it. What good is it if some language has 20 entities rather than 30, if the code base you're grappling with has 10,000.