I don't know for sure, but, I would presume that most makers equip PAT blades to simply the smaller/finish grade and utility sized dozers. The PAT is good at a number of things but it's not great for max strength or blade capacity that the larger, production-emphasized dozers are designed and built for.
I would consider the D-7 to be the start of Cat's larger, production class dozer optimized for maximum capacity per pass as opposed to general utility. Many might not think of the -7 as a "big" dozer but I would as here in ranching and oil field country the most common by far size of rig was something in the D-5/6 class. Cats, TD-15s, HD-11s, etc. Bigger dozers were comparatively rare and far between. In other parts (coal and mining areas) it's not the case, I understand.