Yeah, pretty much all the self-help and pop-psych authors drop Gladwell because it's easy, and if enough people do it, it seems authoritative. Bloggers do it a lot too, then it's just kind of everywhere. With a lot of his work, it certainly would be great if it were true, wouldn't it? So you just kind of go with it, has a nice ring to it. Maybe even inspirational. Everybody can be Supermen. Bill Gates just started early. But it's also BS, and misleading quite a few otherwise well-meaning people that buy into it that are really just wasting their time.
You can look into the Ericsson violinist study to see it as crap, or you can find a more condensed account of why the 10k rule is nonsense in plenty of works, a nice one called
The Sports Gene being a more accessible one, even talking to Ericsson himself in the work, whose opinion is openly along the lines of "That's not what I said and that doesn't make any sense. I appreciate the fame but please stop citing me for this". Good book to read in general, but only took a second to find at least some excerpts on it here: ['Sports Gene' Author Destroys Gladwell's 10,000-Hour Rule - Business Insider](
http://www.businessinsider.com/sports-gene-author-gladwell-10000-hour-rule-2013-8). That author is by no means the only one, but then again you only really need to look at the actual studies to see for yourself.
Gladwell does that with damn near everything. In his David vs Goliath book he tried to use the concept of a U curve as some kind of proof when it was really just an unsubstantiated illustration. I think it was Outliers too where he talked about there being a 'threshold' to how much your height helps in the NBA when that's also crap, and even the relatively short players have 8' tall arm spans like a human bat. You can pretty much tell who will win any high-end physical sporting event by their measurements and natural stats. People know who's going to win before they even compete.
I only mention things like that because I teach a class on Bullshit and Gladwell comes up a lot as an easy target since so many people have read him and he's easy to see through. And if an author so easily cites him and it's not to criticize, that's a red flag that they're not either bothering to substantiate any of their claims, or they have no idea how. And it's causing problems in academia and the public marketplace of ideas.