There are obviously both factors at work though. Exceptionalism does happen, and it is not purely driven by technology. Outside of climbing, take guitar as an example. The amount of excellent players out there on youtube is amazing. Certainly music and the instruments have been available and mass marketed since the 70s at least, but guitars haven't gotten easier to play. Now though, there are a lot of players that have grown up now watching how others play. Not just figuring it out by ear but seeing videos of great players and studying them. It's never been easier to observe great musicians, and so you see plenty of instrumentalists that have progressed very far, building on the shoulders of those who figured those techniques out and wrote those songs.

I don't think the author intended the piece to be "an explanation" so much as an observation. I think that is fine, and there isn't much point in generalizing this observation a human tendency towards sloppy thinking.