People don't smurf because of pathetic scores...they smurf because of good scores that scare off people (or they smurf for other reasons unrelated to score)...
You are correct, people smurf to hide their good profiles but I can't say I have ever seen anyone scared off by a good record. Unless by "scare off" you mean "leave because of clear team imbalance."
In fastest 5v5s I can see why some people get upset about smurfing. 9 people can be starting a game that they think will be an even match, but isn't.
In 3s/4s normal speed matches I don't care. I'll play anyone with any record.
There may be many reasons that smurfing is acceptable, but the possibility of duping unsuspecting opponents to create an unbalanced and unfair advantage is what makes it unacceptable.