That's right Jack, all the functionality you're using in a browser is the one Internet Explorer 6 has. Sadly, most of the people using the browsers you mentioned do the same.
The world you live in is the cave mentioned by Plato. You have never went outside and see there's so much things a browser can do, you're content in your small little world thinking "meh, my browser already has anything I would ever need".
Wrong. You could use a better interaction with the browser, you could use some extra features to make your life easier and stop checking your webmail when you have pop3 and smtp. You could have a lot of things if you would just come out of the cave.
Sure thing, Firefox has the extensions, but Chrome does not. You're missing out on a lot of functionality that you never knew existed.
How are you supposed to know that there is such a thing since you usually search for an extension when you KNOW you need (such as ad-block) but it never occurs to you that you might use a neat clever feature? You're stuck in the dark because you don't know light exists.