[tablespoonsruby]

Maybe they mean that since there are many different feed readers a person could use, a blog can't have a "Click here to subscribe via RSS" link? Most feed readers will have a bookmarklet for 1-click subscribing, but the blog owner doesn't have the ability to make a prominent "call to action"-style button.

[hopesthoughts]

Sure they can, well they can have a link that brings up the feed anyway. What the browser does with it is a different story, and that depends on whether RSS preview extensions are installed. Copying and pasting that URL wherever it needs to go isn't all that complicated.