I'm not naive enough to think there was a "golden age," when everyone was happy-dappy, but I think it's much worse, now, than it has ever been.
I mean, in order to do big, complicated things, you need teams, and teams need to work together. That means much more than just the "hard" skills of individual intelligence, creativity, and discipline. It's also all the "soft" skills, that help the team to retain cohesion, like mutual respect, loyalty, integrity, etc.
The problem is that the example needs to start from the top, and there hasn't been much of a good example, up there, recently.
It's not difficult to imagine people feeling justified in doing bad things to their team, like deliberately writing shoddy code, taking credit for colleagues' work, bailing out, before their bugs come to the surface, or throwing their teammates under the bus.
I always tried to foster a team that had mutual respect, and could focus on common goals, even when everyone had their own motivations and priorities. In my case, it worked, but I know that I was lucky.