i'm Gold level user (with only US POS)

Question: why do availability differ for point-to-point vs a transit involving 2 sectors?

Specifically i'm looking at BKK-HKG on 25th August using Cathay Pacific.
if I search under BKK-HKG the flight is zero out in cheap economy class for most of them.
However if I search under BKK-HKG-TPE on same day, most of cheaper economy class are open.

If anything I would have thought married segment BKK-HKG-xxx will be lower priority than straight BKK-HKG. Or am I mistaken?