> it was easier (for us)

That's not all that unusual when something gets implemented, as people tend to take the easy approach for things that meet the desired goal.

It just sounds like the spec they were writing to wasn't very clear or it was just a checkbox list of features provided to them by marketing. So "lets get this list done then ship it". ;)

The question is whether it was actually easier.

Even a couple minutes of extra debugging takes longer than learning how to add a synthetic primary.