And what do you do if you want to reference how fast the field moves, or why certain methods are not done anymore, but where found 'good enough' back in the days. You would still have to use the old source and cite them...
An absolute cut off doesn't teach you anything...a guidance, how to identify good sources from bad or outdated ones would be much better
I went exactly the same route as you, loved his old videos, HI. At some point I started to listen to the one with Myke (Cortex - had to look up the name) . The first few episodes where quite interesting, but it got repetitive at around episode 50 or so...
Now even the few videos he releases don't really get me anymore