Communication with other people. In my experience, even a two-dev project can be worse (in terms of overall quality, coherence of vision etc.) than if I just di

Communication with other people. In my experience, even a two-dev project can be worse (in terms of overall quality, coherence of vision etc.) than if I just did everything myself. Of course, the more people the more mess the project becomes - but, at the same time, most software is just too large to be written by a single person or even a very small team. Hence, the usual end game is a crappy code base and a product that barely works.