Should I choose RSS or Atom?
Who cares? I don’t. I bet if I asked everyone I had contact info for, only a few would prefer one or the other (though hopefully one in particular).
More to the point, I agree with the underlying argument:
And that being so, it makes no sense to put both standards (if not different versions of each) in the auto-discovery tags, especially for big sites like Flickr and consumer blogging software like WordPress. [...] For the rest of us, our feed readers could care less. So please stop confusing us.
Sadly, I also know the history behind this. Back in the "bad old days", feed readers did not follow the robustness principle. So, websites had to deploy a sort of "inverse robustness principle", to make sure that as many feed consumers as possible could read the content. The good news is that today, any decent feed reader can read most feed formats. The bad news is that no one (or not enough people) have bugged the feed producers (e.g., Flickr) into fixing it. The solution? File a bug and remind them of Postel's law. Of course, only file said bug if no one else has already done so — we don't need to annoy the developers.