It affects everyone, to say that it does not is absurd, for we were all at one time young. It will affect you again too; you're just not on the receiving end of it right now, so I can't say how impartial you are.
Since you appear to be one of those who would subject the innocent to your discriminatory tendencies, consider this; if I told you that you are not physically capable, mentally fit, morally/judgmentally sound and so on and that I happen to know that two arbitrarily different people are, and that you are henceforth subject to those two persons' wills as decreed by law for the next 18 years of your life, what would you say? That you should just take it and not 'whine'? Do you think that just because this subordinate/slave status is temporary that it would make any difference?
Do you not think that this is an obvious case of accusing another human being of being inferior? Do you think that it is so distinguishable from racism, sexism and the like that you are justified in perpetuating it? Doesn't this go against your moral code or something like that?
In this case, the job market, being younger or older does not necessarily distinguish you from the physically/mentally fit for the job; to discriminate based on it is the same as discrimination based on race.