"I Accidentally All The Guns" Trophy Unattainable
To the Naughty Dog QA Team,
This issue is NOT SOLVED.
As of this day, this trophy is still simply unattainable.
After several attempts to get it, none of the approaches suggested by many players worked, so I decided to make non stop playthroughs from start to finish in order to prevent any problems inherent to save files.
I have completed the campaign like this on three different occasions, carefully following the exact guidelines pointed out by a Naughty Dog ADMIN on a related post. You can check the post here:
Such a post has been flagged as SOLVED by the Naughty Dog QA Team, when it suffices to have a look at several other posts like this one to realize it clearly isn't; and moreover, hasn't been for more than a year.
Since they haven't addressed a more than a year-running problem, I doubt they ever will. All I can say is I wish they proved me wrong.