Often, what is described as discrimination just seems to be a sane collection of valid trends:
- Older people are less willing to work longer hours.
- Older people are more aware of their rights as an employee.
- Older people may struggle to pick up new skillsets.
While it would be bad to find myself unemployable due to these factors, I find it hard to argue that they're not generally true. Obviously these are trends, and not things which are always true. Some of them aren't even discrimination against older folks. eg; it's easier to take advantage of younger workers. That's more of an indictment of corporate culture than the older folks themselves. In other words, it's discriminatory hiring, but not discrimination against the group of people who are older.
A common retort here is that an older person might not necessarily fall prey to these issues, even if they can be true in a general sense. I'm not sure what to do there. People don't seem to know what to think about stereotypes. Some stereotypes are true. Some stereotypes are bigoted falsehoods. Even if you're most interested in fairness, how can you know ahead of time whether you've encountered an outlier. Or, how can you know when your stereotype should not actually inform your decision? The social justice crowd provides no answers here: they claim that all stereotypes are as malicious as they are false, and this causes cognitive dissonance when you can tell for sure that some of them are true.
Further, "Ageism" is one of the only isms which can turn back on itself eventually. If I'm racist against black people, there's no chance that I become black later in life and become the target of the ire I've helped foster. However if I discriminate against the older generation when I'm in my 20s, I will eventually become the older generation myself. It doesn't necessarily work out this way in practice, but I would think I'd want to make things _better_ for the older generation, even if that requires unfairness, as I will eventually become older and reap the benefits.