and this has held good just about as long as Ive followed the tour (which is back to the days of Hinault)

The spell around the end of week 1 beginning of week 2 always has the string of stages of 'moderate' difficulty. Not made for the sprinters but won by them 50% of the time. No difficult enough to ever string the peleton out so they all come in with the same time.

Without fail, 1, 2, 3, 4 or 5 riders make a breakaway and typically open up a lead of 3.5 minutes. Never seems to vary much from that.
The peleton maintains exactly the same average speed throughout, and again without fail, gobbles up the breakaway with 500-1000m left (never less, never more) and the 5 guys wind up coming in 20 seconds behind the rest.
So the question is, why do they even bother?? I must have watched this scenario 100 times in 20 years and the breakaway has never won on those stages.