playing devil's advocate: it is easy to claim discrimination doesn't happen when you aren't affected by it--the claim that it is the cause of the individual, no the system, is the usual go-to argument. Try revisiting similar arguments above, but changing them to be about women or black people, and see how they play out.

And for a little flavor, mix in neurodiversity differences. In tech you have people who literally think and act differently. They could be brilliant, but if you expect them to behave and schmooze like your sales team, they are going to wash out. https://hbr.org/2017/05/neurodiversity-as-a-competitive-adva...

Then add to the mix privilege. People who start a few steps ahead, maybe they had better schooling and networks. Somebody who spent 20 years learning the job but starting further behind might be just as good, but just not beginning at the same starting point.

Or, it could just be the fault of the person being old and they should have already succeeded by this point in their life? Don't ask questions, just notice the age and move onto the younger candidate.

Bias and prejudice exists in everybody, we cannot avoid it.