As f the sooty mold...get rid of the best and the sooty mold will stop. I have posted this link before I believe but in any event, here you go... http://baker.ifas.ufl.edu/Horticulture/documents/BlackSootyMoldonLandscapePlants.pdf
The free floating black mold that is always in the air feeds on the insect excreted honey dew (explained at your link) and grows explosively. Looks awful
Not really sure what you are truly saying but unless you have insect infested plants that could be causing sooty mold on your roof, your roof is just plain dirty.
From the IFAS link I posted, "Sooty mold grows on a substance called “honeydew” which is excreted from certain insects such as aphids, soft scales, whiteflies and mealybugs. These insects feed on a variety of landscape plants and
can be found on the leaves and stems where they use special mouthparts to pierce plant tissues and suck
out the juices from within. During this time these insects excrete large amounts of a sticky, sugary
substance commonly called “honeydew”. The excreted honeydew coats leaves, stems, and fruit,
stimulating the growth of sooty mold."
I do not think most people have insects causing honeydew on their roofs. The most common causes of dirty roofs are dirt, tar, acid, jet fuel, and algae.