I don't think that the .gitignore file is meant to reflect anything about when this BASIC interpreter was written, it looks like it's just a MS managed .gitignore that accounts for everything that was ever popular for development in Visual Studio, even things that have been obsolete for decades. In order to handle your most legacy C#, F#, VB.NET, or Visual C++ solutions.
[0] https://continuoustests.com/
[1] https://github.com/github/gitignore/commit/2183a6c531d7085e2...