I've got jeans that I've put 1000's of miles on commuting, and there's no evidence of bike specific wear. The only issue I've ever had riding in jeans is when I get caught off-guard with a warm afternoon and didn't bring bike shorts to change into for the ride home. Riding in jeans when it's too warm can be a little uncomfortable, due to moisture and chafing. Otherwise, no problem, for the commute distances I've ridden, i.e. up to 13 miles one-way.
100% classic drop bar road bikes, by the way.