"Effect. As noun, means result; as verb, means to bring about, accomplish (not to be confused with affect, which means "to influence")."
http://www.bartleby.com/141/strunk3.html
Sorry, derleth. It's not a matter of someone defining correct usage. It's simply a matter of looking at the dictionary definitions of the words 'affect' and 'effect'. Affect simply means to influence while effect means to bring about.
A majority, or at least a substantial minority? (Don't interpret common mistakes as proof of correctness. Most (all?) people who spell 'lose' as 'loose' will at least acknowledge their mistake when it's pointed it out. Nobody thinks 'loose' is actually correct in their "not prestige" dialect.)