Therapy involves lots of talking while life happens. It isn't magic. Sometimes life just sucks for people. Sometimes it's hard on people. Good traits and bad traits put a fuck ton of a huge burden on individuals. There's the whole world. The world affects all people, regardless of whether you know how to see how it does.

They don't make a claim for causation. As they shouldn't.

“this matched sample is used to estimate the causal effect of therapy experience”