Overwatch is a competitive game that attempts to match make you with players of your skill level. That means that new players tend to play against other new players, skilled players go against skilled players. What is seen to be happening with increasing frequency is that those skilled players throw games to lower their skill rating so they can play against those with lower skills.
Overwatch game director Jeff Kaplan said this behaviour hasn’t gone unnoticed and that the team at Blizzard are working on resolving the problem.
On the Battle.net forums, Kaplan explains
We are strongly opposed to this behavior and working on a policy to make it consistently actionable and detectable. Even if you are in a 6 person team, intentionally losing to lower your skill rating is not acceptable.
For now, feel free to use the reporting system and choose Griefing/Inactivity to report this (coming soon to console).
Of course, consoles have the built-in feature which allows you to block other players meaning you should never face them or have them on your team again. That feature did exist on PC as well in Overwatch until Blizzard removed it.
Overwatch is available now for PC, PlayStation 4 and Xbox One.