Yeah I know you can get them if you hunt around, it was just my local LBS didn't have anything else in stock when I walked in on a whim one day. I tend to procrastinate and research and then just go charging in one day and forget everything I've learned. Wasn't even thinking about the skinny end of the cassette.you can still get a 7 speed 12-28 or 13-28
But I don't think anyone I ride with has a 53:11, so I've got that over them anyway, even if their bikes weigh half what mine weighs.