He's talking in the context of console game programming (though it applies to everything). The current generation of consoles has pushed a lot of this stuff to the forefront - with in-order processors and cache behavior in particular exposing the flaws inherent in OOP/Inheritance based paradigms. I'd guess that it's a bit of a perfect storm - inflow of PC developers who previously could rely on hardware upgrades, massive increase in fresh/grad programmers (who are now filling positions on enormous teams of programmers compared to previous generations), and much more PC-like hardware that requires less specialized programming.

It's hugely important in console game programming to know exactly how you're using the system's resources - memory and clock cycles. The styles he's criticizing aren't just bad for limiting resource usage, they're hard to analyze. On top of that, it can be very difficult to silo components of game code (and game engines) behind nice clean interfaces. When you're the engine programmer tasked with optimizing game code because you're the one who knows how to squeeze performance out of the console, you don't want to have to climb up and down hierarchies to figure out where everything's hidden. I've been there - it's especially prominent in 3rd party developers with cross-platform game engines - and it's a nightmare.