The article argues only against sufficiency. Only if you believe that the 10k hour rule is without exception -- that it's not a broad statement about what is necessary for mastery in a broad range of fields across a broad range of talent but instead a precise, ironclad threshold with no other determining factors -- does the article imply anything about the necessity of a certain number of hours.

Any one datum is questionable: How were the 728 hours tracked? Were some forms of practice excluded? Is the master designation in chess equivalent to the elite mastery the 10k rule describes? Is this measurement for an extreme talent outlier?

Neither the insufficiency argument nor the existence of outliers argument have merit against the 10k hour rule, properly understood. One number cannot possibly cover the range of fields, the range of talent, and the range of practice measurements (hour tracking, practice quality). Might this single number still be a broadly useful heuristic? I'm not sure, but this article tilts at windmills unhelpfully.