As I understand, DHT is vulnerable to sybil and eclipse attacks, and not really suited to the task of creating a tamper proof log. If the log and timestamping is not tamper proof, key rotations can be spoofed. Users in the network may need to come to consensus about the ordering of events, such as if signed documents A and B are order dependent. See:
https://news.ycombinator.com/item?id=33639578
Simpler than DHT is just a server hosted in the US somewhere, like what keybase.io is doing, but that goes against my goal of decentralization.