Most economists date the big breakdown in real gdp vs real median wages to have started in the 80s.
The website mainly lists economic factors, but if you look at obesity rates you see a similar trend in the 70s, where quite suddenly obesity rates start rising.
https://www.mdpi.com/1660-4601/21/1/73
I think that while there might not be a single common cause, it would be naive to deny that there could be a combination of events, which mark that time period in particular.
I'm actually curious if this continues through he 2020s. It could have gotten worse or better or been the yardstick by which people were fired or hired.
What makes 1971 truly special is that only goldbugs who really want the gold standard again are insane enough to believe that deviation from the gold standard single-handedly fucked over everything and have the chutzpah to tell you about it even when their own evidence clearly says they're wrong.
I'd highly recommend reading the book "Broken Money" by Lyn Alden for understanding the dynamics of what played out.
But I think you are also likely correct that one could create a similar website about, if not any year, certainly many different years.
I think this website is being rather disingenuous in the way it presents things. Not only in the way they cherry picked a bunch of charts which show drastic changes after 1971 (and which may or may not be related), but also in the way they leave it to the reader to "do their own research" while framing the question so as to ensure that 5 minutes of googling will yield the answer they want to plant in the reader's mind.