It would be silly to argue that good drafting isnt important. Heck its essential! Smart free agent acquisitions doesn't necessarily handicap your team. Lets look at the Commanders who have picked up guys like demean Jackson, garçon, Colt McCoy, duke ihenacho, dashon Goldson, Stephen Paea, chris culliver,and most recently josh Norman. These are just a few of their free agent signing over the last 3 years. They won the division last year, and are still competitive this year. They have cap space and don't seem to be handicapped by any of their free agent signings.
I'm not saying they are great, but they have used free agency to fill in key spots and it doesn't seem to have put them back much.