I agree with the "getting older" scenario - all body skin gets drier and less elastic - hence the droop.
Not a laughing matter I suppose though -- cuz the situation would cause the "labia minor" to fold under in various ways and pinch. Blood cut-off from bits and pieces, edges etc.
Sigh.
I think that people wanting/feeling the need to have this type of surgery may have had the condition prior to cycling but are now noticing it more b/c of starting to ride? Cycling seems to be getting more popular than ever before.

Keeping blood circulating in the area would probably be a helpful thing to prevent this -- or put it off as long as possible.
So...I say: Have lot's of sex -- or whatever -- float your boat! Keep that circulation happening! Nourishing, oxygenated blood ... everywhere