“When a company does something like this when it is under pressure, it becomes a way to distract attention by appearing to do something,” said Mitra Ardron, the head of the decentralized web project at the Internet Archive, which has hosted the Decentralized Web Summit the last four years.

Many people working on decentralization projects are concerned that Twitter and Facebook are trying to align themselves with the work’s countercultural spirit without giving up their enormous power.

“The monoliths see it as a threat to their model, so they try to weave in the concepts into their own products to maintain control,” said Eugen Rochko, the founder of Mastodon, a competitor to Twitter. With around two million users, Mastodon has been one of the most successful alternative projects.

Mr. Dorsey said Twitter was just starting to look at the idea and had committed only five people to it. Facebook has moved ahead with its Bitcoin-inspired cryptocurrency and has beefed up encryption, but the company has otherwise taken few steps to decentralize its services. Mr. Dorsey and Mr. Zuckerberg, though, have frequently discussed decentralization, suggesting they have a personal fascination that goes beyond business interests.

Mr. Dorsey also hired a small team at his second company, Square, to work full time on Bitcoin, without any commercial responsibilities. And he recently announced that he was hoping to take an extended sojourn in Africa to understand how Bitcoin was working there.