You are missing point...
Today has surely cost something, even if they didnt attack each other. It sure tired some people out. Both some of the captains and domestics, that might just had enough to stay with the group today. That might drop on Saturday for just a small shift in pace up Port Bales for example. Saturday was always gonna be the real test this week to see who is still in contention going into 2nd week.
To put someone into red today you would probably had to put yourself into red, a maximum effort. For what? 20s. Makes no sense. They are managing their efforts to have the most energy where it will count the most. No one is truly that much better than anyone else that they can just attack and attack. It costs too much. Easier to just have them drop on a stage because they gone into red so many times to just stick with.
I didn't miss it, I just thought it made no sense.
Of course those in the best condition at the start of the race, should attack at the start of the race.
Waiting for your opponent to recover and/or hit his form peak, is completely illogical.
Also, it is not only about the GC riders, it is also about their support riders.
The more "off days" you give them, the better they will be in the few stages that truly matter.
This is the time when you use your lieutenants, who are still close on GC, to force Ineos/Jumbo to work hard, it is also when secondary GC teams can gain valuable time for their captains.
Everyone healthy who does not use a stage like today, is really riding this Tour with 3rd as their primary target.