Matt,
Yellowing is a legitimate issue. It is very acute for non-ventilated areas that aren't exposed to daylight. This could be an off gassing issue or a UV exposure issue.
The first time we saw this was when a customer opened a small cupboard near the ceiling and flipped it around so that it was juxtaposed to a white painted surface that had plenty of sunlight exposure and air ventilation. The difference was like night and day. The yellow looked like a lemon next to the white.
Yellowing does not appear to be a major issue for the majority of our kitchens. They may all yellow somewhat in comparison to what they looked like originally but this metamorphosis is so gradual and uniform that it does not seem noticeable.
Something to bear in mind is that it is hard sometimes to separate our expectations for today's chemicals with accepted truisms that live in our lizard brain. Benjamin Moore Satin Impervo was, for many years, the standard go-to paint for oil based enamel. In order to stay compliant with VOC laws the chemical composition today, however, is not what it used to be. The marketing and name recognition is the same but the product is different.
It's like Purina dog food. The label never changes but the contents depend on what's cheapest on the commodity market any given day.