Interesting observation. Not sure about the voice recording in the ECR, but I think NTSB is sorely lacking the appropriate expertise in marine matters. All kinds of expertise available on contributors on this panel as well as locally with the NA/ME firms.
I have read some of their incident reports on aircraft stuff and sounds like a real SME.
I do not know enough on the subject, but I now wonder if these marine reports from them are like gospel to the non-marine public.