I use the vinegar + milk all the time for buttermilk and think it works great. However, we use whole milk 100% of the time. I suspect that author was probably using 1% milk in all the tests. Using whole milk I get the depth of a real milk flavor, plus when it curdles from the vinegar added it gets nice and thick.
Merry: I don't think he knows about second breakfast, Pip. Pippin: What about elevenses? Luncheon? Afternoon tea? Dinner? Supper? He knows about them, doesn't he?
I didn't read the link but I've always assumed the acidic component is the reason buttermilk is used. I've used 1/2 & 1/2, whole milk, soy milk, cream....anything works with acid IMHO, but I've never done super fancy baking.
Thoreau said, 'A man is rich in proportion to the things he can leave alone.'
I've used milk and vinegar or lemon juice, yogurt (I didn't thin regular yogurt), dried buttermilk powder and frozen leftover buttermilk. If you use buttermilk powder, you need to whisk it into the dry ingredients and then add water when the buttermilk is called for in the recipe. If you try to dissolve it in water, you will be trying for a while and may or may not get it all dissolved. If you don't whisk it into the dry ingredients, you will get lumps of powder in the batterr and they don't bake out. I had hard white bumps in a Texas Sheet cake once. Not great. But other than that, they all work.