You’re probably already aware that there have been literacy requirements to vote in the past in some places in the US, but those were actually an excuse to disenfranchise black people. https://history.iowa.gov/history/education/educator-resources/primary-source-sets/right-to-vote-suffrage-women-african/voter-registration-literacy

Literacy tests were banned by the Voting Rights Act in 1965. There have been recent attacks on that law including the 2013 Supreme Court case Shelby County v Holder which overturned election oversight in jurisdictions with a history of racist disenfranchisement; and Allen v Milligan from a couple months ago was an attempt to overturn gerrymandering restrictions, but thankfully it failed. Combine that with continuing voter disenfranchisement (for example far too few polling places in Atlanta leading to black voters waiting in line many hours to vote), and there is no doubt in my mind that if literacy tests were legal again they would be used the same way they were in the 60’s.

Personally I think history has shown that we get better leaders when more votes are counted.