Even the smaller competitors like Bombardier would have an interest in this, even if they are not the manufacturers of similar sized aircraft, a loss of faith in the aviation industry hurts everyone too. Plus suppliers etc.

As for the investigators (I know you meant FAA, not FCC), we have a similar issue in medical devices - you need seriously well educated experts to perform the investigations, and it is hard to find any without industry experience which wouldn't look good on paper. The solution is to try as hard as you can to not have ex-employees audit their ex-bosses, but it isn't always possible so we accept some overlap. It doesn't mean these people don't take their job seriously.