there is a legitimate economic (I'm not advocating this) argument for hiring younger. Younger devs are cheaper, often more idealistic and more willing to work unpaid overtime. Throw some cheap perks in there (catering, beanbags etc) to encourage them to spend all their time on company turf and I'm sure it adds up to a greater company benefit than hiring an older dev even allowing for experience/skill difference.

All because they are at the healthiest time of their lives. Also that means cheaper healthcare plans

There is a lot of wisdom to be found in people who do not make their place of employment the end all be all of their existence, even if for a period of time.

There's certainly a lot more to life than work. Doubly so in your 20s.