I wish some of my apples were scabby, it can turn table apples into half decent candidates for hard cider. McIntosh in particular are known to improve significantly (for that particular use) the scabbier they get.
Link to a study on that subject (it’s in English):
The study found that apples with scab had higher levels of certain anti-inflammatory compounds, apparently as a result of the tree’s immune response to scab infection.
Someone like @Richard would be better equipped to evaluate the study than I am, but it seems worth noting that it compared scab-infected fruit with non-scab-infected fruit of the same susceptible variety (Braeburn).
This makes sense in the context of the study, but it seems to leave open the question of how the levels of anti-inflammatory compounds in a susceptible variety like Braeburn would compare with the levels of such compounds in a resistant variety (say, Goldrush).
In other words, if you’re interested in higher levels of anti-inflammatory compounds, do you actually need visibly scabby fruit, or could you get similar (perhaps even better?) results with resistant varieties that have been scab-exposed?
I guess this would depend on whether the resistance in a variety like Goldrush was based upon the same kind of immune response?
The thing to understand is that most table apples are breed to remove tannins, which are polyphenols that make the apples more resistant to fungal infections. One of the working theories for not fertilizing hard cider orchards (one backed by a whole lot of testing) is that it enhances both the sugar concentration and polyphenols as the tree reacts to somewhat stressed conditions.
McIntosh apples are good for blending on hard ciders. The scabby ones can actually pull off a pretty decent single variety cider.
You would have loved the Macs my Dad grew when I was a kid. He did spray Captan a few times a year, but many of the Macs would still be half covered with scab in bad years. Mom would make apple sauce out of the few that were worth cutting up. I’m pretty sure that tree is why my Dad started cutting down fruit trees and eventually only had a single pear tree left. That Mac was just a huge vector of apple scab.