There has been a long-standing fight between the Haskell.org committee and the developers of Stack, regarding what should be the "default" option to install Haskell to be displayed on the homepage. Many Haskellers think Stack is a strictly better tool, but the Haskell.org committee thinks that the Haskell Platform is still worth mentioning on the homepage. The Stack team could not convince the committee for months.
In the end, the Stack team decided to create a new Haskell community, haskell-lang.org. One of the Stack developers who had contributed to the original haskell.org even said "I don't approve of the current haskell.org, nor your use of my design".[1] It seems that they are trying to replace the Haskell community in the same way how Stack replaced Cabal. This also includes a GitHub organization, an IRC channel, and even a subreddit (/r/haskell_lang).
[1] https://mail.haskell.org/pipermail/haskell-community/2016-Ap...