If you’re a publisher only then RSS/Atom makes much more sense, especially if you want to retain ownership and control over content you created. If control is not important to you and you want to incorporate social aspect into your website (comments, reactions) then ActivityPub seems like a convenient way to go about it.

One thing that I strongly disagree with author of the blog post is the discoverability aspect. Yes, initial federation kind of sucks but at the same time your readers on Mastodon will be able to boost it and increase your reach.