Firstly, we should distinguish two types of smurfing for the up-coming analysis. The first type involves leveling a new account, from 1 to 30. The second one is playing ranked games after you've reached level 30.
Let's first discuss level 1 to 30 smurfing.
Right now the percentage of smurfs on the ladder compared to mains is not large enough to ruin a significant amount of someone's games. Most smurfs are in the level 1-10 region, so the absolute start might be a chain of games in which you are forced to sit back and watch how much more experienced players try to carry their teams. Beyond this level, you're likely to most often face evenly-skilled opponents because your MMR starts adjusting accordingly, and the percentage of smurfs at that level decreases rapidly.
In other words, you might get a rough start, but other than that most of your games should be you facing opponents that have roughly the same level of experience and skill as you.
Now let's discuss what you actually mentioned - smurfing in ranked.
I think when you enter ranked, you have officially stated your intention to compete with other players and see how effective your strategies and skills are compared to others. This means learning the game and having fun are suddenly not the only reasons to play the game anymore - otherwise you might as well play normals. When competing with others, winning or losing is irrelevant. Your win rate and amount of games played determine where you end up on the ladder. Now realize what these two factors depend on. Games played depends on how much time you are willing to spend on league - clearly this is not relevant to our analysis about smurfing. Win rate depends on the difference between your "true" skill compared to your "current" skill, which is measured through MMR. So long as you are positively or negatively influencing game, you will get to your "true" MMR - if you play a large enough amount of games. This argument breaks two fallacies: 1. "My teams are bad, thus my MMR is much lower than what I deserve i.e. I am stuck in 'Elo Hell'"; 2. "I am trying to climb the ladder, but high-elo players come down here and prevent that."
So long as there's not enough smurfs to make a "lower" MMR actually "high" because there's simply that many high-skill players in there, you will not be negatively impacted on your travels through the ladder. This all stems on the fact that you will benefit just as much from smurfing - or more generally good/bad teammates - as you will lose from it.
The only determining factor on your climb... Is you.