I've thought there was more opportunity in fundamentals up until Warren Buffet and Ben Graham's the intelligent investor became well known. More people tried to use these methods, thereby increasing demand and decreasing the upside on securities that meet Graham and Buffets criteria. The stock market today is very different from when they got going, although long term I don't know that anything has fundamentally changed, even before robot traders there had always been random and unexplainable noise.
Wait, if there was more "opportunity in fundamentals" back then it would mean that stocks were further away from their fundamentals, right? That's pretty much the opposite of what the OP is complaining about.
I'm actually not thinking about a specific period, I was just referring (maybe naively) to the time before computer assisted analysis became so widespread (before the eighties, I guess).