Sometimes you need to do some database operations at once. A simple example: User-A transfers money to User-B. Updating just one balance at the time creates a risk of data desynchronization. What if the first DB operation goes well but updating the second user’s data fails? Sounds like a hard to catch vulnerability.
Nowadays, with an ever-growing number of web services, we tend to overload Web apps with external resources. As a result, it decreases page load speed and affects SEO score. There is a pretty easy solution for that.