Dodgeman, mesh tape has been with us for a long time now, maybe there's a way to put it on w/o cracking. When I first came upon this phenomenom I had same thoughts as yours. Why?? If fiberglass is stronger! I did an autopsy on one of these cracks, what I saw was the mesh mostly intact but never the less a crack was there. Hmmm! As you know the seam between 2 sheets of drywall creates a void which we want to bridge with tape, paper tape bridges this void 100%, but mesh tape does not, I would say if one were to add up all the material in mesh that actually bridges the seam it probably wouldn't come close to covering 50% of the seam. You have the little mesh squares, so you have material-void-material-void etc... There's absolutely no strength in mud, so when you have mud trying to cover a seam which is still at least 50% uncovered you get cracks. This is the only thing I can come up with why it cracks with mesh. All I know is I've seen mesh jobs crack many many times. Maybe someone more learned than myself can explain why this happens.