On occasion we say (write) something like “go part way up the street” and it feels perfectly natural. We might also say something like “that’s only a part-way solution,” and that’s still okay. Now look at this sentence:
This is a rather common change in English. We go from separate words, to hyphenated, to one word. (One of my favorite examples of this is the change from to-day to today.)
Anyway, this tendency to move toward single words is fairly common.
Here’s the picture that the sentence is about:
PS—Here’s a word that has finished the transition to one word, and the writer gets it wrong.
Maybe he split “shortcoming” to make a nicer line break; but then, he should have hyphenated it.