I agree.
I also have an example of why this may be the case.
I remember finding a really good SFO-EWR-SDQ (or something like that) deal on UA. It came out to around 3cpm ($250ish). I needed a few more miles that year, so I was looking at booking it for a weekend.
I could also get an all-inclusive resort for two nights for about $70/night.
However, on Expedia, booking the flight and hotel together (same flight/fare class, and same resort), it came out to around $275.
I've seen other cases on OTAs where adding a hotel actually DROPS the total cost.
How do you allocate AQD when the flight is $800, the resort is $800, and you paid $800?
The alternative is booking separately, but I imagine you wouldn't like what that does to your out of pocket cost
