Excellent long article (a book chapter) on the topic by the expert.
"Disruptive innovations, in contrast, donâ€™t attempt to bring better products to established customers in existing markets. Rather, they disrupt and redefine that trajectory by introducing products and services that are not as good as currently available products. But disruptive technologies offer other benefitsâ€”typically, they are simpler, more convenient, and less expensive products that appeal to new or less-demanding customers.
Once the disruptive product gains a foothold in new or low-end markets, the improvement cycle begins. And because the pace of technological progress outstrips customersâ€™ abilities to use it, the previously not-good-enough technology eventually improves enough to intersect with the needs of more demanding customers."