I have played this game for a long time and I think I may have run into 1 MAYBE 2 actual smurfs who were way too good for my elo.
Most people who say they are smurfs either aren't, or they really aren't nearly good enough for it to have a noticeable impact.
What I am tired of, is people calling others smurfs when they get stomped. They assume the other player is clearly Diamond on a smurf account, discounting the possibility that they themselves either didn't play very well that game, or the other player is better than his elo suggests and is trying to climb out.
In my attempts to climb to gold for the end of the season I played my heart out and I had several people insult me for "smurfing" and whining both in-game and post-game. Some even went so far as to send me friend requests to talk more trash. It's extremely disrespectful to discredit the other player's performance like that.
Two friends and myself were thrown into low silvers after this season's placement matches, and I assure you all of us belong in high golds at least, but we simply don't have the time to play enough games to climb quickly (adult life is a b****). If you take into account all the trolls and seriously bad players who got lucky and are ranked higher than they should, it can take a long time for someone to climb to their proper elo.
In short, most people you think are smurfs are probably just players who have yet to fight their way up through elohell.
(Side-note: I don't think anything less than high platinum main can even be seriously considered a smurf. The level of play at <=Gold is seriously bad.)