I think the fans & press deserve equal blame for the initial hype. At some point I saw a supercut of things Sean Murray said, then the resulting headlines and Reddit posts.

In an interview, the journalist asks: "Will you be able to play with your friends in a shared universe?" The answer: "Well...we hope that eventually there will be at least some multiplayer functionality, though maybe not on day one...like maybe you could explore one another's planets or share pictures or something."

Headline: "NO MANS SKY WILL LAUNCH WITH MULTIPLAYER!"

Reddit comments: "I'm already forming a guild, we're going to play as bounty hunters chasing down other players who are pirates in glorious multiplayer space battles!!"

There were tons of examples of that. Journalists would poke and prod for a soundbite, take it out of context and exaggerate it, and the community would just go batshit with their expectations.