They’re incredibly convenient. It allows smaller groups of people to accomplish more in a shorter amount of time by providing a standardized interface that does a great job of integrating with their existing environment. When translating database input and output into server-side representations, you have two options: build and maintain the process yourself or use a mature tool designed for that specific purpose in your server-side language. I strongly prefer the latter, as do many others. I find that most people critical of ORMs end up creating their own narrowly focused, weakly tested ORM-like database compatibility layers in their backend. These have caused more problems than ORMs ever have.