Granted, compost tea as a foliar disease control is a crap shoot. There is no way of knowing if a particular tea brew has the right species of microbes in sufficient numbers to be effective against certain leaf, stem or fruit pathogens. Of course targeting applications with specific microbes with known pathogen fighting abilities that can live above ground on plant surfaces makes more sense.
Compost and other types of teas are more valuable as a ground application where they can greatly help restore balanced biology to depleted and abused soils or soil-less container mixes. I think it's important to grasp that teas are not just about bacteria and fungi, but it's also about protozoa and bacteria and fungi feeding nematodes which are critical to nutrient cycling. Without them and larger critters like earthworms and arthropods plants grown under organic conditions would never get the all the nutrients they need.
Compost teas are a pretty complicated subject that has nothing to do with haphazardly throwing everything but the kitchen sink into a brew.
Dr. Elaine Ingham's
"The Compost Tea Brewing Manual" is required reading for anyone wanting to understand the biology and experiment with compost teas.