Its not that it isn't obvious, just that sometimes your focus is on other things and you forget to think of these things. At large organizations you might have

Its not that it isn't obvious, just that sometimes your focus is on other things and you forget to think of these things. At large organizations you might have a designer, product manager, front-end developer, and back-end developer and you can isolate their thinking to individual parts and make sure not to miss these things. In a smaller organization your front-end developer might also be your designer and if they are focusing on scrolling performance, responsive design, or unit test coverage the UX might end up being something in the back of their mind and gets less time/focus. Development is all about making trade-offs with your time, you rarely have a "finished" product. A lot of times what we do is build out MVP as quick as possible and then A/B test changes to KNOW they are making a difference. A lot of UX things that I assume are obvious end up losing in our A/B tests.