My mum needed a D&C because her uterine lining started growing unevenly during pre-menopause. Again this was something diagnosed via ultrasound and had symptoms (ongoing bleeding).
My first child and my first angel were both conceived first try. After the D&C I bled for 10 weeks, waited 2 cycles then it took a further 4 cycles to fall again. I wasn't made aware of asherman's before my D&C but was very worried I had developed it. My second pregnancy didn't proceed well (slow rising levels, slow growth and constant bleeding) and I miscarried at 9 weeks.
We TTC straight away and conceived our son after 4 cycles. I personally felt like the natural miscarriage did a better job of 'resetting' than the D&C but that is just based on my experience.
If I had another MMC I would see if I could have a hysteroscopy, then they are not going in blind like they do with a D&C.