Sadly, some blogs have begun to rely on RSS functionality in the browser, and don't place an RSS link visibly on the page. That makes it rather difficult to subscribe.
The same way that some browsers do it. There is a meta-tag in the page, which describes which feed formats are available, and where to find them.
For one thing, it shows you the whole history of the feed -- even when the XML itself contains just the few most recent items.
And then the author complains that it's hard to use and people aren't taking advantage of it. Jerk.
In fact, I'd bet that part of the reason many people don't use the address bar feed button is because the practice of having links to feeds is so common, and anything on the page is automatically more obvious than something out in the browser chrome.