As a direct victim of this, I think it is more about beauty and non-business reasons. I was interim VP of IT for a company in Houston, with the potential to become permanent. Most of the execs (myself included) lived in other parts of the country and would only fly in once a week or less frequently. When they came into town, it was important that they "socialize" every night, all night, including lots of food, booze, and (dare I say it), women. It was clear to me early on I would not be able to keep up and didn't see any point in trying.
I wasn't "quite what they wanted" but they loved me (because I got things done and made friends in the organization quickly) and decided to hire a permanent VP for whom I would work. Of course, the new guy was young and beautiful and was willing to go out partying all night when the (other) execs were in town.
I'm sure you can guess the rest of the story. My severance agreement contract had a clause that said I couldn't pursue any action because of age discrimination. The fact that it was even there was further evidence to me of the real reason for the severance. Since they had moved me to Houston with insufficient funding for the move, there was no way I was gonna NOT accept the severance.
Thing is, the new guy came in and spent orders of magnitude more money than I had (my first objective had been to keep spending level), and didn't accomplish any more than I had accomplished, even with all the extra spending. After he fired me, he later left the company under unfavorable conditions (related to spending).
Now I find it VERY difficult to get a job. I've actually re-written my resume to remove experience. I do fine with the modified resume up until the face to face interview after which I suddenly stop receiving any communications at all and my phone calls are ignored. I know it's about my age (I'm not particularly ugly and have excellent hygeine). I don't fumble around for words and am moderately articulate, being comfortable in front of people. They just don't want an old dude when they can have a young, beautiful person.