That's an extraordinary claim to make without any evidence. The entire business model of a newspaper is that they report facts.
They can do this by reporting facts, but generally it is easier to do this by reporting stuff people want to read, which includes facts and non-facts and things that may or may not be factual. This also generally involves summaries which aren't factually true as they drop relevant details, but which are close enough that people tend to tolerate them (see any reporting on a scientific paper ever).
Also, an "an anonymous source said X" could be factual, but the implication is that X has some level of truth when the only known fact is that in reference to that X was said by an anonymous source.
You've never regularly read UK newspapers I take it?
I wish that was their primary purpose, a few of them never let a story get in the way of their agenda.