Because blacks have lower average scores on them.

Whites also have lower average scores on them. Lower than Asians and Jews.

At the elite level this would make a huge difference. At the state level not at all.

What do you mean by "whites". American "whites"? The last IQ report has many Asian countries at the top followed by "white" European countries. Whites and blacks are such generic terms. There are many different types of white, black, asian, etc peoples that have different cultures and phenotypes based on the region.

https://worldpopulationreview.com/country-rankings/average-i...

That site is a mess. Shows a chart where the average IQ is 82, links to a page saying the average IQ is 100 (which is the original design). Also cites a eugenicist and thinks that worthy of a passing footnote. Frankly, I wouldn't trust anything I read there.

Can we somehow blame this on oppression?

Lead poisoning lowers your IQ; blacks are more likely to be exposed to it. (https://www.dw.com/en/lead-poisoning-reveals-environmental-r...)

And this is the same reason whites rank lower than asians and jews?

No need. Just attribute an unmeasurable quality such as creativity to your racial group.

The Griggs v. Duke Power Co. decision (https://en.wikipedia.org/wiki/Griggs_v._Duke_Power_Co.) makes them legally problematic.

Because they're largely accurate in the aggregate and project outcomes quite well, and no one likes this.