I respectfully disagree with the notion that sharding makes resource usage somehow less important. Sure, it allows you to overcome the limits that would apply to a single node, but if you stop caring about using resources efficiently (e.g. memory / disk / network bandwidth), it's not very different from building huge and expensive single boxes.

Also, I don't think the blog (or me) suggested going back to using autoincrement IDs. There are other (better) options.