Originally Posted by
Pittsextra
I struggle to see how an independent board investigating the facts of the matter need to circulate drafts...
You are struggling because you are attempting to analyse and pronounce on areas of which you have no knowledge.
The short answer is that circulating the draft report to involved parties for comment is required by ICAO annex 13. All countries' accident investigation departments (who are members of ICAO) have to comply with that. If you disapprove I suggest you write to ICAO and explain that you think they are doing it all wrong.
The purpose of the process is to allow comments to be received. These comments may or may not be used to amend the report, that is up to the reporting body. It helps prevent misunderstandings or minor factual inaccuracies from making it into the final report.