Google's John Mueller asked if it would help if a site timestamped its content and pages using blockchain. John responded "Google doesn't use that." In short, he said Google does not use blockchain for search.
He added "These setups have come up from time to time. Since they don't affect Google (positively or negatively, as far as I can tell), if you find them useful for yourself, there's no harm in using them." I am not sure if blockchain is a fad and will go away but Google doesn't seem to depend on it.
Here are those tweets:
Google doesn't use that.
— 🍌 John 🍌 (@JohnMu) March 8, 2021
These setups have come up from time to time. Since they don't affect Google (positively or negatively, as far as I can tell), if you find them useful for yourself, there's no harm in using them.
Forum discussion at Twitter.