"Over the last five years, one in six bookings have shifted from those under 30 to the 30-39 age bracket, according to holiday company Thomas Cook"
Thomas cook sell packages, I'd say a great deal of people going to Ibiza in the younger age group just get Ryanair flights and a cheap hotel.
I'd also say under 22/23 are and would be more at home in Malia, Kavos, Magaluf, Faliraki, Napa etc......
On the other hand, 30-39 is probably the age group you can actually afford a proper Ibiza holiday, with several club nights and events etc...
To be honest I've been to Ibiza much much more since I turned 30, easier to afford now.
Probably some truth to the story, but basing it on Thomas cooks bookings doesn't make sense.