UCI finally approve discs.

[Cycleops]

It had to come but many are still using rims:
https://janheine.wordpress.com/2018/07/29/disc-brakes-in-the-tour-de-france/

 

[Tenacious Sloth]

The fact it was a very dry tour probably helped riders decide on rim brakes.

If the weather had been wet in the mountains I reckon more riders would have chosen discs for the descents.