A lot of us do understand how sad this can be.
Leo used to have the most beautiful ears of all of my dogs–very long and very full and deep black. Because of his scratching, he eventually removed the top black layer leaving sort of a mixed grey underlayer and also, the scratching would create mats very easily and he could easily get his hind leg caught in the mats, causing more distress. So I had to take the decision to keep his ears trimmed short at puppy length. This has allowed some of the darker black to regrow and also just makes life a lot easier for him. Other than that, he has managed brushings with no problem and still enjoys this and will fall asleep having it done. But I sometimes look at pictures of when he was one or 2 years old and really mourn those beautiful ears.
Lily, who also has SM, is in the same boat with her ears–I have to keep them very short as well and her coat tangles more than Leo's, so it's really important to keep the ears short and free of knots. She is also very sensitive around her legs and hindquarters for grooming so it has to be done very gently–I always carefully hold the base of the hair and then gently work on the mat and straightening out the rest of it and this seems to work for her most of the time. But increasingly, I just snip out mats and I also keep the feathering on her hind legs quite short so that there is less to tangle or brush.
One thing to consider is to look for those really small slicker brushes that are for cats–I have one that is only about 2 inches wide–as it is very useful for getting into mats and delicate areas rather than using a normal dog sized slicker brush. The tiny brush means you are not pulling other adjacent hair and can just focus on a single mat.