I believe incontinence IS on the rise. In decades past, people were shamed and outright forced to obtain and maintain their continence. Even when that meant extreme and painful procedures. Though yes I also believe it was also under reported too, and for good reason.
With acceptance on the rise, and the stigma on the decline, awareness of the same old trends is increasing without finding an actual increase in incontinence cases. Except that would also mean not as many people are being driven towards continence. There IS an increase number of people who would rather allow themselves to become incontinent. Thereby driving up to total cases by a slight margin.