Not gonna lie. That hasn't occurred to me, but that is a pretty grave discrimination as well.
It might be even more insidious because there's a strong justification that stupid people are stupid because of their own volition. However, in reality, there's element of intelligence that's purely genetic and there's nothing a person can do.
As with all things in life, a determinist can spin it so it's no fault of the individual. Someone might have little control over their beauty or their intelligence, or even if they are a jerk, or even if they are violent and abusive.
The reason I bring it up is because I think there is an important distinction between a illogical bias and a simple preference.
People are very preoccupied with weeding out bad biases, and often mistake preferences for them. Things are only complicated more when egalitarian ideas get mixed in.
There's nothing inherently wrong about wanting a beautiful life partner or to watch an attractive Entertainer. Those are legitimate preferences. The only problem is when individuals place that as a higher priority than something else that they actually want more.
> what about discrimination against stupid people?
It is also very common, but also very frequently is discrimination that goes to the core of the overt purpose of the decision being made. As discrimination is simply having any factor play into a decision, the usual problem is with (1) decisions whose motivation is to cause harm to a group, or (2) decisions in which factors like membership in a group are weighed that are not germane to the overt non-malicious purpose, which cause an (unwarranted by the purpose) adverse impact on the group.
It might be even more insidious because there's a strong justification that stupid people are stupid because of their own volition. However, in reality, there's element of intelligence that's purely genetic and there's nothing a person can do.