A big part of why they're not interesting is because they generally pay a small fraction of minimum wage. The median is about $2 an hour. So I don't think MTurk serves as an adequate example of the type of job the op referenced.

Much of the work done by stay at home moms pays less than minimum wage, though: Etsy stores, clipping coupons / general penny pinching, these MLMs.

I do think that the main difference is that the mechanical Turk work is just soul-crushingly boring.

Clipping coupons is soul crushingly boring as well. I also run an Etsy store as a side activity and make about $25 per hour, 5-10 hours a week. Median for all Etsy is still about minimum wage, which, again, is significantly better than MTurk @ $2 an hour. And I'd argue the high volume low margin work for Etsy stores looks every but as soul crushing.