.NET Core is cross platform, it was created with ASP.Net as the driver and web development is not about exe files. "dotnet run" runs your code, on any platform, that's one of the default intended ways to run code. If you want a platform-specific executable you've done more work and made the code less general. If you also want to package the entire .Net framework into one binary on any platform, why is it unbelievably impossible to understand that this is more effort and desired by fewer people, so isn't as easy to do?
.NET Core is cross platform, it was created with ASP.Net as the driver and web development is not about exe files. "dotnet run" runs your code, on any platform, that's one of the default intended ways to run code. If you want a platform-specific executable you've done more work and made the code less general. If you also want to package the entire .Net framework into one binary on any platform, why is it unbelievably impossible to understand that this is more effort and desired by fewer people, so isn't as easy to do?