When I mix mortar for stone work in the wheelbarrow, I put the water in first then add the cement, mix it in, then the lime, mix it in, then the sand and adjust the mix to get the consistency I want. The reason I do this is to keep the dry ingredients from sticking in pockets in the corners of the barrow.
With cooking or baking, we have really nice tools to scrape the sides and bottom of the mixing bowl, removing any chance of having pockets of unmixed dry ingredients anywhere.
When we pour the wet on top of the dry the dust expelled during the mixing process is reduced.
It may produce a better distributed mix to add the wet to the dry, for example when I make pancake or waffle batter I put the egg and milk mixture on a well in the dry stuff and then add the melted butter. If I did that first, the milk mix, cooling the melted butter might make it clump up a bit before I could get the dry stuff stirred down into it. When I put the wet on the dry, I always mix immediately, incorporating the wet well into the dry before any separation occurs.
Seems like when I was a baker (a long time ago) we added the wet ingredients to the big commercial mixers first and then added the pre formulated dry concoctions a bit at a time as the dry became incorporated with the wet. Which is the same way we used to make mortar using a small cement mixer.
Other than as noted above, have never run across a regular cook book recipe that calls for adding dry to wet....at least that I can recall.
Actually never thought about it before, hope this helps.