To give them some leeway - it seems that wasn’t for lack of trying to get more statements from other people involved, and they did try to provide statements by all involved parties were relevant with what they had available.

That was an interesting summary of the happenings since last time, and I appreciate them delving into the criticisms of their last documentary - which I think was overall also a good work of research overall, even if the mistakes they made (and acknowledged) were real.

This paper seems to suggest so, but also mentions “Previous empirical work on this topic, which shows a diverse range of estimated effects […]” - so it seems like other factors will play a role. (Disclaimer: I read only the abstract)

EDIT: Another paper seems to back up those finding.