LogFAQs > #973029710

Basically:

Nomura wanted darker and edgelord-ified Final Fantasy for "Versus 13"
Communications went dark over the course of 7 years, over which he was still ostensibly the director
Tabata came in after the rebrand to 15 was announced and was met with a staff at the end of its rope, overworked and constantly having to redo what they'd already done
Nomura, in classic Nomura fashion, couldn't decide on his own story, changing it significantly a few times each year, at one point demanding to turn 15 into a musical after he saw Les Miserables.
Nomura got to fuck off to KH3 later and leave Tabata with a steaming pile of shit -- and as the public face for the game doomed to mediocrity as a result.

Seriously, Nomura is a blight on the damn company, and Tabata couldn't pull off the miracle Yoshida did.

That's not what more trustworthy accounts of the development say, is the thing. So...yeah I don't take it seriously. By all reckonings, the staff didn't have a direction, but it was because there were countermanded orders coming from on high, above Nomura. Nomura consistently insisted it was going to be the tale of two rival noble families, which is why that plot is going to be told in KH4, still. You don't like Nomura, but you're actually, factually wrong about his responsibility in XV's failure. He didn't get the initial version finished, but it was due to a lot of issues elsewhere.