It is engineering if you approach it as such. I'm currently building a large web app as a personal project and I'm approaching like building a machine. Custom middleware and authentication, optimizing queries, optimizing caching, scheduled tasks, etc. Every part of it needs to run harmoniously with all of the other pieces. Anyway, I'm not setting out to change your mind. But software development can very well be treated as engineering depending on the sophistication and nature of the task.