Documents for QlikView related information.
In this paper, I try to explain the key synthetic, i hope will be helpful .
This is a pretty good description on synthetic keys by Henric Cronström Synthetic Keys
Also, synthetic keys themselves don't necessarily consume more resources than normal keys, but you are right to advice that they should be avoided. Reason is that while they don't affect the performance, they do make the data model harder to understand and therefore, since they don't bring any benefits, it's good style to live without them.
Thanks.for your comments.