Poorly Defined Antagonists
It's difficult to say who the main obstacle is to Danny Rand achieving his goals. Is it Ward and Joy Meachum, his childhood friends turned chief executives of Rand Enterprises, who are determined to protect their empire from this barefoot pretender? Is it Harold Meachum, the wicked business partner of his late father who, following his death and resurrection, is controlled by the Hand even as he secretly pulls the strings of Rand Enterprises? Is it Madame Gao, the Hand leader introduced in Daredevil who orchestrated the death of Danny's parents and keeps Howard Meachum under her thumb? Is it Bakuto, Colleen Wing's mentor and leader of a Hand faction who's building his own army in a "secret" college campus-size compound in the middle of New York City? Or maybe it's the DEA, which is sent after Danny in the penultimate episode, for no other apparent reason than to delay the inevitable showdown(s) of the finale.
Marvel's Netflix dramas tend to be a bit too long, requiring the introduction of a new threat in what should be the third act (for instance, Diamondback on Luke Cage). However, Iron Fist never settles on a primary antagonist, which not only muddles the overall story but also Danny's arc. Despite their early actions, Ward and Joy are little more than pawns of their father, with the former developing into the first season's most complicated character, and the latter teased in the last moments of the finale as a potential primary antagonist.
That should leave the enigmatic Gao and the cartoonish Harold as Rand's main foes. After all, they have deep, dark connections to his past, and have the most to gain by his defeat. However, once Bakuto steps fully out of the shadows as the leader of a faction of the Hand, Gao is effectively moved off the board (and into a cell), and Harold is demoted to a secondary player. That poses multiple problems for Iron Fist's story, not the least of which is that Bakuto becomes Colleen's antagonist, not Danny's, but it's Davos who ultimately kills -- make that "kills" -- the Hand leader, robbing the others of closure.
Likewise, the final showdown with Harold Meachum doesn't complete an arc for Danny; it's Ward, long manipulated by his father, who ultimately ends the threat. The Immortal Iron Fist is left with little to do but try to return to K'un-Lun, his parents unavenged.
Does The Defenders change any of that? The antagonists of the miniseries are clear, although (as you might expect) their goal is not. The Hand, the ancient criminal organization that menaced both Daredevil and Iron Fist, poses such a threat to New York that it unites four disparate heroes for a single purpose: to save the city they love.