Because it's insufficient?

https://github.com/github/gitignore/blob/main/Rust.gitignore for example still falls victim to basically all of the issues specifically called out.

I don't like them, because they contain all sort of crap, that never even enters my projects, but they don't include things they should include, like the silly ".vscode" folder so many people commit without thinking. Also usually using these templates one avoids thinking and knowing what is ignored, until one accidentally commits something special to the project and boom, creating a huge hassle.

These do not include os generated files like his first example, .DS_Store. I do use the templates, but I have a gist that I add to every project of os generated files that may work themselves in.

I like https://www.toptal.com/developers/gitignore because I can mix programming language files with OS ones

In my experience these templates don't cover enough and are always faulty. Not only that, most real-world projects use many different programming languages and markup languages.