You know what's amazing? That Armstrong dude never had a crash in any of the 7 TdFs he stole. I hardly remember that guy ever crashing period.
It's a combination of all things culminating in an increased number of mega crashes.
- rider behavior + DS behavior (shouting on the radio telling their riders to get to the front)
- stage profiles (like a bunch sprint stage with little cols & descents 30k from the finish)
- modern road bike technology (like disc brakes)
- road surfaces (some of these roads turn into a literal ice rink in rainy conditions at this time of the year)
- street furniture etc.
Armstrong has remarked a few times how back in his day the descents were taken carefully, whereas now they're drilled. This Dauphiné stage 5 was the last opportunity for the sprint teams so the chase was on irrespective of the road conditions. That played a role as well. We already saw the break riders have traction issues/crashing/slipping, so the peloton had been forewarned.
I could see that crash coming from a mile away & knew it would happen once they hit the descent of that small cat 4 climb, so I was not surprised at all.