I'm only speaking for myself here, but I see federation as a means to create a large platform that isn't controlled by any single entity. Whether or not federation will be useful depends on whether there will be posters, and who those posters will be. Federation lends itself well to social media applications because social media is driven by users creating accounts and posting. Any change in state - be that a new post or comment being created, something being upvoted or downvoted, something being reported, etc - fans out from the server it happens on to other servers that are federated with it. Contrast this with what OP mentions their friends do with their website: "[T]hey have them only to publish contact info, opening times, and a couple of photos of their business." In this scenario, what data would be getting federated? These sound like static sites.

It could be that OP is asking for something closer to a business's facebook page. In this case, some federated software might be better suited for their needs than others, but I don't think that's the same thing as a corporate website.