Yeah it's a matter of interpretation of author's post. You rarely need the actual value, until you need to debug or trouble-shoot manually. So, you make it such that people don't need to know what is inside and how it looks, until they really do. Also, for main entities like user or account or something that might need to be uniquely identifying some global container in human readable monthly reports or documents, int id is very useful, no questions there. No need to do long where int can suffice.