The new Apple TV does not come with any support for application-based web browsing, making social media apps like Facebook and Twitter essentially useless.
A post from developer Daniel Pasco explains that WebKit, a framework that makes developing apps with web viewers easier, and UIWebView, a tool that makes the development process of said apps simpler, are both missing in tvOS, the operating system on the new Apple TV. Any developer who wants to include a web viewer in their app would have to put in an incredible amount of work. Apple has not announced a version of Safari for tvOS either, meaning links cannot pass over to Apple's browser instead.
Social media apps like Twitter, which won't be able to open shared links, are now pretty much a non-starter. It is possible there could be a limited version, but at the point where you cannot interact with most of the shared content on an app, it seems unlikely that the developers will bother. Even if it did launch, without the ability to open links it will be an inferior experience.
It's disappointing news considering that even the Nintendo Wii, which launched in November 2006 with no high-definition support, is able to browse the web. Pasco outlines a few reasons why Apple might have done this: web browsing on a giant screen may have been difficult, a potential security hole has been blocked, and developers will not be able to push out apps that are simple wrappers for a website. All apps will have to be fully designed for tvOS. Whatever the reasoning, it seems that the new Apple TV might not be the complete Internet-from-the-sofa experience people were hoping for.