Back when I last used C#, which admittedly is over 10 years ago, .csproj files were written in XML so they were annoying to edit. It was difficult to understand the structure of them, and I'm not sure if they were documented very well.
Just compare a .csproj to something modern like a Cargo.toml and you'll see why someone might think .csproj is awful. It is immediately obvious what each section of a Cargo.toml does, and intuitive how you might edit or extend them.
Also, just talk to a C# developer, I bet over half of them have never even edited a .csproj and only use visual studio as a GUI to configure their projects.
Just compare a .csproj to something modern like a Cargo.toml and you'll see why someone might think .csproj is awful. It is immediately obvious what each section of a Cargo.toml does, and intuitive how you might edit or extend them.
Also, just talk to a C# developer, I bet over half of them have never even edited a .csproj and only use visual studio as a GUI to configure their projects.