It does, but rarely in the way people expect. Social is weak at capturing people who are ready to buy right now — that is what search does. It is strong at three other things: being remembered before the need arises, proving you are real when someone checks you out after a referral, and re-reaching people who visited your website and did not enquire.
Judged as a direct-response channel against search ads, social usually looks poor. Judged on its actual jobs — recall, credibility and remarketing — it earns its place. We set the expectation before we take the budget.