well that's an interesting take. granting that the fediverse is decentralized, is it democratic?
my instinct would be to say "no: i don't need to hold a referendum and get a majority vote in favor before bridging my site to the network: i just do it and each other site either federates with me or doesn't." that sounds more anarchic than democratic.
on the other hand, the vast majority of the network has all settled on ActivityPub as a protocol. one could say that users and developers "voted with their feet (or their actions)", coalescing around that protocol and now it's effectively legislated (in the sense that a democracy would legislate English to be the official language, or for Pacific Time to be the regional timezone).
but AP could still be displaced/improved without any appeal to authority. Misskey added all sorts of wacky protocol extensions and it didn't need to ask permission from anyone else on the network: whatever useful features it adds sort of disperse outward. i wouldn't describe that as "democratic". if someone really wanted to use a political metaphor, i guess you could say that decentralized networks federalize innovation? still feels like the wrong class of metaphor though.