“The use of like for as has its defenders; they argue that any usage that achieves currency becomes valid automatically. This, they say, is the way the language is formed. It is and it isn’t. An expression sometimes merely enjoys a vogue, much as an article of apparel does. Like has always been widely misused by the illiterate; lately it has been taken up by the knowing and the well-informed, who find it catchy, or liberating, and who use it as though they were slumming. If every word or device that achieved currency were immediately authenticated, simply on the grounds of popularity, the language would be as chaotic as a ball game with no foul lines. For the student, perhaps the most useful thing to know about like is that most carefully edited publications regard its use before phrases and clauses as simple error.”
—Strunk and White, The Elements of Style, 1959 ed., pp. 41–42.