The early web very quickly gave rise to curated directories of information and stopped working on word of mouth. Yahoo was a directory before it was a "search engine". AOL was a curated walled garden. Web rings were a thing, great for playful discovery, terrible for finding a specific thing. Heck for that matter, web ring banners are arguably just interactive "banners ads".
Word of mouth also requires a high degree of trust in the person spreading the word. Otherwise you get things like youtube "review" channels that are just paid reviews. Or the reddit bot farms where suddenly everyone in a given part of the web is suddenly dropping references to their new Bachelor Chow™ recipes. You can't even trust the news. We all know about submarine ads, but even without that, you can't ever be sure if you're hearing about some new thing on the news because it's really the best/popular, or because they just happen to know a lot of the reporters.