Some people just don't like it and it's fine. But the poster was asking why there is a trend of people who don't like it and that was more what I was speaking to.

Depending on where you are from, though, many things that are sold as aioli are, for all intent and purposes, fancy mayo or are point blank made from mayo.

Very traditionally, aioli is olive oil dripped and mashed into cloves of garlic with salt in a very painstaking process. Non-traditional aioli often has that plus lemon juice, vinegar and/or egg mixed into it--which effectively makes it mayonnaise. Mayo usually is made with an oil that doesn't have such a strong flavor as olive oil, but not always, the rest of the ingredients are eggs, vinegar, and/or lemon juice. If you have an immersion blender, it's definitely worth putting these ingredients in a tall plastic cup and slowly dragging it up. Add garlic paste and you will have half the aiolis you will ever get if you order it at a restaurant.