I believe you ! But such rumours live for long, obviously !
Even DNA analyzis wouldn't extinct them, I guess, as we can see for Charles' case. As elena-maria-vidal explained, such stories may be grounded on political purposes, a lot of people were highly concerned in spreading them. Nowadays, there are other reasons, sentimental, nostalgic, touristic... I think that, on one end, people need to daydream and, on the other hand, some have less noble interests in making others dream !