Within the last 20+ years one of about 5 wooden spoons in our household has cracked even though they're always cleaned in the dishwasher. I don't see the problem.

It really depends on the wood used. Some should absolutely, under no circumstance, be expose to a hot + wet environment. Some, you can put in the dishwasher and they are fine. I do use a lot of wooden cooking utensil and most of them go in the dishwasher. But I do have some nicer wooden spoon that are made from a more precious wood that I would always wash by hand.

Another thing is that a loot of wooden utensil are made in several piece stick together with glue. A lot of cutting board are made that way for example (especially the cheap ones). Most glue are not very dishwasher safe. It might be fine for a few wash, and then you end up with pieces of a cutting board.

Just to echo this comment. I don't put my wood cutting boards in the dishwasher because they dry out and crack. Wood utensils have been fine in the dishwasher. They seem much less prone to cracking than cutting boards and, when they do crack, I just throw them out and replace them with cheap new ones. I see wood utensils as a wear-item.