This is probably due to how they might have their hosting set up - there are places that can host wordpress for you, with addon support and all of that, but it would only host wordpress. They almost all let you use your own domain.
But I don't think many of them would also host a forum for you. And they probably don't want to go to the effort of paying for a forum host as well, so they go for a free one. Free forum hosts generally don't let you use your own domain.
This is nowhere near cluttered. Everything is presented with clear separation, you can easily make out sections of content. A main header image, a single Youtube video, a 3 card info section ("important notes"), and a very web standard 2-1 main/side bar layout for news posts.
The only real criticisms I would have with this is that the news is so far down on the main page that its pretty hidden under the fold, and there is no clear Call to Action anywhere near the top when a user first loads a page. They have a tiny recruitment link in the nav, which is fine, but it blends in with the other links. There is no "Join Now" or anything like that at first glace. The general idea is that average people will spend barely any time on any one page, so you have to have something prominent, obviously stands out, calls on the user to take an action, and that should never have to be scrolled down to be seen (but that's more marketing type stuff the design specifically I guess).
Aside from that, the pitch black to stark white is a huge contrast. While I don't hate it, i think they could play with more grey colors and make a bit easier on the eyes.
Over all, not a bad website, and I've seen way worse. Its pretty easy to get a decent design with Wordpress though since it has such a wide user base, and tons of themes.