Exactly this. There is a fine line with regions and they have their uses. As an example, I was working on a project a while back that had StyleCop rules set up

Exactly this. There is a fine line with regions and they have their uses. As an example, I was working on a project a while back that had StyleCop rules set up so stringently that nothing could live in the same file, no enums, structs, extension methods, nada. The amount of files you had to create when adding new functionality (even a minor one) was mind boggling...