On the marketing document analogy, a service might reduce the overall effectiveness of these types of lines as a signal. Right now these lines are a differentiator not so much for their literal content but for the signaling that the person who uses one knows about how resume writing is advancing and is tapped into that. Sure, the content matters too but as hiring manager I can tell you these lines get similarly superficially scanned like the crappy vague lines do. That is, after reading the hundredth resume that day, the main takeaway is of the form "ah, this person knows about making their resume lines specific and concrete...+1...this other person doesn't...-1" Once everyone catches on, this signal becomes less useful.