It is such a tradition that as the "pavé" sections deteriorate, the cobbles are replaced by hand instead of using asphalt to make the road surface more useable for modern farm vehicles.
I have a buddy who’s an avid cyclist (I have to confess I was the world’s slowest Cat 3 for 15 years as well), who traveled to France in the 80’s and drove up to the Arenberg Forest section of the P-R course. He got his bike out of the car, took one look at the pave (a dry beautiful day) and put it back in.