It certainly makes them idiots, from the perspective of artificially restricting their audience; AFAIK it's very simple to publish on OpenVSX, there are no extension changes needed. Most devs I know use VSCodium, not VSCode.
And how many devs do you know? What percentage of all the devs in the world does that represent?
If you know a million devs who mostly use VSCodium instead of VSCode, that might be significant. But I'm guessing you just jump to conclusions about almost everything based on your own bubble and lack of critical thinking skills. Then you can just call other people idiots while patting yourself on the back for being so smart.
