Reasons not to use an auto-incrementing number for a primary key

Question

I\'m currently working on someone else\'s database where the primary keys are generated via a lookup table which contains a list of table names and the last primary key used

Answer 1

My main issue with auto-incrementing keys is that they lack any meaning

That's a requirement of a primary key, in my mind -- to have no other reason to exist other than identifying a record. If it has no real-world meaning, then it has no real-world reason to change. You don't want primary keys to change, generally speaking, because you have to search-replace your whole database or worse. I have been surprised at the sorts of things I have assumed would be unique and unchanging that have not turned out to be years later.