Mayo has some very good applications: it goes well on a hamburger; it's an easy way to make a good grilled cheese. The issue is that nobody wants to eat a condiment as the binder in a "wet salad." In fact, I mostly just don't want a wet salad; I'd rather eat mashed potatoes than a potato salad, and having googled a Waldorf salad, it sounds like it would be outright better with the mayo just left out. The issue with the author isn't that people younger than him dislike mayo; it's that they dislike it as the "wet" ingredient in an otherwise milquetoast dish.