I think the explanation why P/E is being largely ignored and derided is far simpler. PE has become “useless” because every other indicator is “useless”. The market has repeatedly rewarded, to stratospheric levels, companies without profits or even expectations to be profitable in the near future at all. It’s quintessential Irrational exuberance. So from the point of view of traders and the new “gambler class investors” looking at any of the finances is an utter waste of time. And I don’t see this behavior stopping until we see a dramatic and long lived market correction.