Having an outstanding resume is essential. It doesn't matter how it gets to outstanding, but it needs to get there. The problem is that most people can't see themselves objectively and positively enough to produce a resume that does the job that it's supposed to. I didn't know this until, years back, I got into HR and learned how dismal the situation is. Early in my career – outside of HR – sending off resume after resume and wondering what happened on the other end, I was clueless. When I got into HR and realized how poorly most people presented themselves, it all made much better sense.
When you're on that side of things, you quickly learn what works and what doesn't. Essentially, employers work under the premise that past performance is the best indicator of future performance. Resumes that speak to accomplishments immediately communicate an "achiever" approach to work. Sure, resumes that speak to tasks and responsibilities can say a lot about you, but they say the wrong thing.
It's not that what you did wasn't important, it's that a list of tasks does not differentiate you from the competition.
I see it day after day, resumes full of tasks from (for example) Project Managers who insist that their 5 page resumes are warranted because "this stuff is important" and from Executive Assistants who think it needs to be communicated that they have arranged travel. Hiring managers will expect that Project Managers know how to design and develop a project; they'll also assume that an EA worth his/her salt will have made travel arrangements.
Use your resume to focus on those things that communicate how you've raised the bar.
Hiring Managers and HR want (need!) to see you achievements. Moreover, they need to see what differentiates you in a sharp and powerfully formatted resume. One that's dynamic without compromising resume conventions. No pictures. No color.