What's wrong with Rider?

It's not a Microsoft tool. For a supposedly fully cross-platform language it seems pretty bad to only support first-class developer experience on Windows.

You're right. They did until recently, but it was bad. Now they seem to have moved attention to creating a great experience in VSCode but some of it may require a MSDN sub (they seem to be making the core experience free, with paid extensions to give more Visual Studio-like features in VSCode).

I believe that vs code is the way they want you to do .net on windows as well.

The tooling is all CLI based anyway so do what feels best. :)

Is it "wierd tho" that Microsoft would have better support for development tools on their own OS than on a competitor OS?

It's absolutely weird because that ship has sailed. The paradigm is to hook you into the platform which you can't do if you are hostile.

They support ‘dotnet’ cli, just not an IDE. But we’ve got Rider

Rider is so much better than Visual Studio or Code in my opinion, but I understand how the price could be a deal breaker.