He’s right, but the other point to make is that RSS isn’t mainstream yet. Email and the web are mainstream, but took years to catch on with the general public, even after being widely available. RSS is widely available, but only used by a minority of the general online population.
That will change, as the tools used by the great unwashed pick up and highlight RSS functionality. That’s not Newsgator or Firefox, but IE and Windows.
It’ll change as the influential early-adopters persuade others.
And it’ll change as the standard is sorted out — not just the XML, but how it’s advertised — that orange button needs to be ubiquituous, just like “www” and “.com” in URLs are now.
So if your site doesn’t support RSS now, it’s important to get it doing so very very soon.