Web2 succeeded because Web1 protocols haven't been developed to withstand abuse. For instance, the email protocol (Web1) hasn't got an extension that would enable receiving emails only from authorized senders. As a result, email is heavily abused by spam and phishing to a degree that only a handful of large email providers can effectively deal with it. The centralization of email services is typical for Web2.
RSS (Web1) hasn't got an extension that would enable access restriction and following. As a result, centralized proprietary ad-driven social networks (Web2) took over.
HTTP (Web1) hasn't developed a micropayment mechanism. As a result, the current internet is monetized through all-pervasive ads (Web2) with all the terrible destructive downsides that come from ad-driven media.