[fullstackchris]

I think it is also out of laziness or simply forgetting to step out of one's own shoes sometimes. It's sometimes hard to explain all the technical parts of a project well to a newcomer who has 0 experience with a particular project when its something you've been working on for months at an in-depth level. We're all guilty of skipping small parts of explanation simply because subconsciously we've done it so much, or it is such a 'trivial' component of a given process or system.

These poor explanation and documentation patterns I find most often in open source (though it does indeed occur in industry software as well). A huge number of GitHub READMEs reflect this notion (even in npm packages, for example, that are downloaded 1000+ a week!).

To the author of software, the README may be perfectly clear, but for first time users of the software, it can be totally lacking and/or just plain confusing. I always try to be explicit as possible in my instructions and documentation in hopes to battle the field's poor explanation reputation. It's definitely a skill I always try to work on and get better at.