>>7409410He was booked pretty well from the start getting to fight and team with main eventers. He got to feud with Blue Demon and Black Shadow. Santo fought Black Shadow in the biggest mask vs mask match up to the point. Demon became the 2nd biggest lucha star ever going down a similar path and Shadow was a big name too. Shadow lost his mask though and he broke down quicker because he worked a more high risk style, plus he didn't have a legitimate heir to carry his name on like Santo did.
Santo also happened to be one of the top guys when wrestling got on TV in Mexico and anytime a new technological medium comes along and gets hot, the people on top really benefit from it (See the NBA with Magic/Bird, Hulk Hogan in the 80's and others).
The movies and comics also really helped. He was kind of the Mexican version of Batman.