That's true, but the part of the reason that it's a big problem that various news sources are so slap dash is the way the human brain works. Once a person has read a news story, it's more difficult to displace those "facts". People generally believe the first story they read, even if they read a correction later. Even if you are aware of this type of cognitive bias it still occurs. Obviously it can be overcome but it's much better to try and get the most accurate version first.

When combined with other biases, this is why polls routinely show many people still believe some story that was reported even after it has been widely discredited.