As an employer, if I have 2 candidates for a job, one is 17 with no experience and the other 25 with several years experience, the only way for the younger person to be the more attractive to employ would be a lower wage to reflect the lack of experience and the level of training needed.
Employing a young person is often very training intensive, as they usually have a lack of working experience and life experience that and older person could draw from.
Housing benefit wise, a young person will more often than not have few possessions and a home with their parents, so if they want to leave home at a young age they need only limited space and resources given to them. I should imagine it would also serve as an incentive to not remain on benefit. On the other hand, a pensioner who has contributed to society, usually born children, have a lifetime of possessions etc absolutely should not then face the shame of being forced to rent a room in somebody else's house.