You're right, it has been that way for about the last 20 years. But I have the same perspective as
@Extinction. Attacking in feed zones, nature breaks, and some other times has always been frowned upon, and while I think not attacking the yellow jersey was also, it didn't feel like it does now. It felt a lot more cutthroat in the 80s and 90s anyway. Ciapucci would attack in tunnels, feed zones, etc. Pissed people off but there was no penalty, he kept doing it.
But this idea that you wait for a competitor who crashed his own damn self into a ravine was...let's call it "new". And that was either Lance at best trying to be magnanimous, and at worst totally playing head games with Ullrich. I'll let you catch up and destroy you again kinda thing.
Then everyone else got it in their head that you can't attack here, you can't attack there, you always have to wait for the yellow jersey, chaingate, more whining, lots of clutching of pearls, etc, etc.
Today's action I think was more the old school, where the group waited for a race leader in a race where the stakes aren't that high, and he might not have been at fault. I think that's the right thing. But if a rider crashes on a descent (or similar) 'cause they were under pressure? Tough. Pour it on and eliminate them from the race. You attack in yellow and your chain drops? Seeya. Shite happens.