The problem is that if you didn't fetch the file at the right time, you will lose some history after rotation happens. At the very least, it needs a standard way to deal with that (like a mandated date-based URL format?), which has to be specified in the format.

Also, no DM and no @-replies. For those, you need a registry of some sort, but decentralized registries enable name-squatting.

Before you know it, you have reinvented the WWW, except limited to 140 chars.