They may not know how to do it right, nor have the means to get a software development team started on the project. To some extent, "if it works, don't fix it"

They may not know how to do it right, nor have the means to get a software development team started on the project. To some extent, "if it works, don't fix it" applies here... until it doesn't work. I don't blame domain experts for scratching their itch and solving problems in whatever way they see fit using their own knowledge and tools. It's the way that many software projects get started, and where new opportunities get discovered. These are good things.