I wonder if zot protocol is more lightweight than activitypub protocol, but knowing that zot has more features than activitypub I guess it shouldn't be more lightweight? Anyway whether it better or not why not make Mastodon version based/working on zot instead of activitypub for diversity sake. I think one protocol is not enough, and I heard activitypub is not that good, that some people are sceptical about it being the best solution for decentralized email-like social network that we want, - from technical point of view, maybe too over complicated to be really sustainable, I don't know.
@fisunov apart from the terrible name (there are numerous things named "zot", and especially a scientific service with an API called Zotero) it doesn't look to bad. Although the documentation is bloated and tough to read it at least is specific.