What types of companies were you interviewing at? I've really never seen anything but ageism in the favor of younger people.
Somehow I doubt everyone else was treated like a prodigal son when they were younger and my experience was just bad luck or poor preparation. When this was happening in 2007, I was able to get about 20 interviews that only ever amounted to 2 job offers.
Although my situation was somewhat complicated - applying for entry level project management work and having a philosophy degree.
I started hiring people when I was 26 (now 37), and I can tell from my own experience than my first attempts of interviewing people older than myself were quite uncomfortable -- so it's not surprising that I tended to avoid such applicants.
As a self-employed consultant I have found that some people get nervous when they find out my age (25, started when I was 23) - presumably because consultants are selling their expertise and judgment to someone who lacks the skills or confidence, else they wouldn't need you. Confidence is a big part of what you're selling. Nobody gives a shit if the 3D engine in a game is written by a 18 year old genius living with his parents, but you're less likely to present him to enterprise customers. Hiring grey-haired sages oozing confidence probably makes business sense for consulting companies - skill may well be secondary; besides, measuring performance is notoriously difficult in the first place.
Similarly, the recruiter may not have been terribly confident themselves and were looking for a proxy who would project confidence.