Stew in the oven or on the stove, does it make a difference?
In the oven, that heat is coming from all directions more or less equally. On the stovetop, the heat is coming only from the bottom. This can potentially cause convection, and almost certainly requires occasional stirring (especially for larger batches), meaning that the ingredients are being moved around. The combination of the ingredients being heated more when they're at the bottom and the movement can cause them to start breaking apart, and generally cook unevenly.

Personally, I only find this to be an issue with beans and meat (and it's not something that's going to cause failure; it's really just a refinement) but if you are making an especially large batch of stew, you may want to try the oven.