Many manuals don't list a lot of things. Sometimes its because their results were not suitable, or consistent. Sometimes because a given load is not what the majority of the public is looking for. Sometimes something doesn't get listed simply because there was none on hand to test when they did the testing.
I think it's more realistic to say that there are just too many powders to test. With some 60+ powders that can work in the 9mm, testing them all would be too expensive and time consuming (= too expensive because you have to pay the people to do all those tests).