From my reading of OP's question, it sounds like he's asking, if Latex as an overall collection of software/ utilities were made by one person or group, why would they choose to put PDF titling in
hyperref, a package seemingly with the more concise goal of providing hyper referencing?
So, the best answer might be to point out that Latex is a collections of SW/ utilities/ tools made by many independent groups, usually working without a higher-level organizing structure.
So, in this case, I suspect that kind of like Alan said above, whoever made
hyperref probably felt this PDF titling/ author listing functionality wasn't easily accessible in any other package, and figured that since they knew how to do it anyway, they'd just throw it into
It's not that somebody explicitly said "I'm going to put PDF titling in
hyperref rather than some other more obvious package."