I'm not a big fan of this whole community splitting action, but to think that it's been undertaken as a coup d'état to take control of the community by a commercial entity is verging on tinfoil hat territory.
And you know what? Stack is a fantastic tool for newcomers, we use it exclusively for our commercial Haskell projects and it's changed our development practices for the better by a long way. Something that built today I can be sure will build in a year without changes - cabal has never been able to guarantee that. I'm really glad someone has put in the huge amount of effort to make a better Haskell build tool, it's been far too long coming.
What makes them "official"?
https://web.archive.org/web/20050728010349/http://www.haskel...
It is in no sense the "official" outlet for GHC. It's an outlet that promoted other people's work, and anyone else is welcome to make a new outlet of their own.
https://web.archive.org/web/20090129200859/http://haskell.or...
which immediately lists implementations and compare it to
https://web.archive.org/web/20100402011002/http://www.haskel...
a year later you will be reminded of the rather spectacular struggles that preceded the ghc-centrism of haskell.org . The change was closely associated with the appearance of the haskell platform, and the arguments very similar to those concerning stack and stackage. If you want paranoid theories of corrupt commercial motives in that case, I can produce several incompatible ones for you to choose among.
The former is now virtually uncompilable (and was never complete), Hugs is officially unmaintained, nhc hasn't seen a release since 2010 so is not under new development.
While there was discussion over this, it doesn't at all resemble the set of arguments more recently.