Perhaps a nod to “truthy”?
It’s a perfectly cromulent word.
See Posts #4 & #10.
Enter the Flagon - I respect your dislike of “smidge” (it’s a silly little word I tossed in for the sound of it in my head in that post upthread). But that’s different - “depthful”, per pulykamell (thanks puly!) is a weird, obscure word that exists on the fringes. Smidge is just a silly word that should only be used in silly situation. “Impactful” is a jargony word used by Business Tools who want to make actionable statements at key inflection points 
Depthful is just bad.
I wonder if the writer threw “depthful” in hoping that Colbert would see it and start using it on his show.