One of the best things about reddit was looking for answers or other users with the same problem as you, and since Google didn’t really help with that anymore and instead insisted on giving you business results, the best practice was to put your search terms in followed by ‘reddit’ and you’d find your answer.
Being decentralized will make it harder to just use “search + reddit” because you don’t know if it’s “search + lemmy.world” or “search + beehaw” or “search + kbin.” Also, each admin is in charge of their own Robots.txt.