Because, in part, you can't have the one without the other. You can't talk about limits without having a model for infinity. They are inextricably entwined, each idea leading to the other.
It's sounds to me like you've simply been put off by loads of badly written Pop-Math articles that attempt to boggle and astound, without showing the real truths as to why the whole subject is really, really cool, and simultaneously, useful and practical.
Brian Clegg's book on infinity gets good reviews, but I haven't read it. I'm thinking of starting a blog series on it, but with everything else I have on I may never really get to it.
But as I say, in your specific case it really depends on your background. If you're really interested perhaps you could email me more details on what you've studied and what you've read, and I can write some brief articles by way of reply.
I have no problem with the concept of infinity in terms of limits, but that's not what this article is about. It's about the concept of infinity itself. And that is what I disagree with.