I'd argue that the Fangraphs article was remarkably poor, in that the author saw a total of maybe 100 swings, all but three or four in batting practice. He then made his entire assumption on that and one "conversation" with a scout who also doubted Hamilton's swing/ power.
(Others don't. Witness this AL scout, when asked about Hamilton's hit tool:
There's no analysis done at all. (And on Fangraphs, that's inexcusable.)
Were he to have done actual analysis, he may have noted that many players similar to minor league Hamilton have enjoyed a bunch of success at the major league level despite beginning their careers with no power/ slight frames.
Players like Rafael Furcal, Brett Butler, Tony Fernandez, Phil Rizzuto, Richie Ashburn, Harry Hooper all showed little power (Iso slg of .114 or below, all of them) in the minor leagues or early in their major league career. Yet, all became All-Star level producers despite that lack of power. The 1970s alone are littered with no-power, high-obp, high-SB leadoff guys. Heck, Lou Boudreau has just as much-- if not more-- in common with Hamilton than the erstwhile Dee Gordon.
(I also question his acumen on Hamilton's defense, as he claims the kid has a wet noodle for an arm;
Hamilton threw 92 mph from the mound as a HS player.)