In a discussion on smurfing on the Blizzard forums, Jeff Kaplan stepped in to clarify Blizzard’s opinion on second accounts (which is fine) and boosting and throwing (which are not fine).
Having a second account you play on is fine. New accounts very rapidly adjust to play at the proper skill level.
Doing anything to manipulate your internal MMR or Skill Rating (i.e. Boosting or Throwing) is not fine.
Penalties for boosting and throwing are about to increase dramatically. Please report the behavior (reporting is being worked on for Console but is not ready yet)
Boosting, the act of letting someone else play your account so you can achieve a rank based off their skill level, is a controversial topic in online gaming. While nearly everyone agrees it’s ethically wrong, players who hunger for rank exclusive rewards and prestige will continue to sink money into this act. Blizzard plan to respond by removing them from the ecosystem altogether via bans.
Throwing also allows players to artificially lower their MMR by losing intentionally. Attack Torbjorns with suspiciously poor turret placements (or no turrets at all), AFKers, and melee only Mercys are likely going to face increased punishment from Blizzard.
These changes are especially important as the Overwatch amateur league rolls out and players will be aiming to climb to Master. The fewer boosted Master players and the easier the climb to Master, the more pure this competition will be.
Blizzard has been consistently cracking down on toxic behavior since launch, including changing all instances of ‘gg ez’ to a randomized phase that mocks the typist.