Musing further upon my post yesterday, and wondering about the endurance of these two narratives about sex in history, it occurred to me that they do have something in common.
They are both about posited attempts of a patriarchal system to exert control over women - in the case of the chastity belt, specifically husbands attempting to ensure the fidelity of wives, in the case of hysteria/vibrators, the notion of dealing with disruptively hysterical women by giving them a good seeing-to with a medically-approved and scientific device.
And both get subverted. Most tales involving chastity belts are about the woman managing to deceive her husband nonetheless, while the hysteria/vibrators narrative implies that women took a procedure intended to pacify them into appropriate womanly docility and turned this into private enjoyment with personal appliances.
This is a much more widely applicable gendered narrative of male desire to control and sly womanly subversions, with added sauciness. No wonder these have legs.