It’s “web site”, not “web sight”.  This phrase was coined to say “this is the place where this web content exists”.  “sight” makes no sense at all.  I suspect this has become common because people hear somebody talk about a “web site” and never see it written down.  So, let’s blame the English language with it’s ridiculous propensity to have words that sound the same but mean different things.  Still, people who get this wrong should still be beaten mercilessly with a fungo bat.