If the joint were pervious so water could soak into the ground underneath that would be a plus.
The ground underneath is still going to be 6-12" of concrete.
In these parts, the freeze and thaw cycle would have the road surface and subgrade a shambles every spring and fall, and hell to drive on all winter (until the trucks broke everything down and mashed it flat).
Actually it wouldn't. Its the water seepage into the concrete or asphalt roads then the continuous freeze, thaw, freeze, thaw....etc. that destroys them.
The severe weather we had here in Michigan this past winter had a devastating effect on our roads........
With that being said, I firmly believe that our roads are built/repaired with inferior materials so as to cut costs and allow the local road companies such as John Carlo to underbid all their competition and continually repair and rebuild them.
The counties and state have no desire to build long lasting roadways which would cost more in the short term but would certainly save the drivers tons of money in costly damage to their tires, wheels and suspensions.........
When all logic fails as to why our roads are so bad, follow the money trail.........