The upper classes of Argentina used to vacation in Mar del Plata, but in the 40s, with Peron, it got very popular (aguinaldo and vacaciones laws allowed to the poor people go massively to Mar del Plata) so the upper classes, frightened, wanted to avoid every contact with the masses, it really changed the landscape, and they moved out to another place, more cuter, more quiet, and that will became exclusive with the years.
So during 60s, 70s, 80s, and 90s, Punta was some kind of a hidden gem, very exclusive, quiet, very homogeneous from the social point of view.
Argentine old upper classes, unlike other Latinamerican countries, always were inspired by the european model of society, taste, elegance, sophistication, etc people linked with "el campo", who lived in Recoleta, near Avenida Alvear, with French architecture, who went to the Jockey Club, 100% antiperonistas, with some kind of rejection to american way of life. That the old rich.
That started to change in the 90s when the "american way of life" enters, all this new richs, a lot of new richs (and new poors of course) and a lot of traditional wealthy families who got poor. Money changed of hands, the financial bussines replaced the agro bussiness, the new richs were people who traditionally belonged to middle class, and had totally different uses and habits of old richs.
In the 90s, with all these new richs Punta got much more popular. Also, a lot of people from Chile and Paraguay started going every year. In the 2000s brazilian people discovered Punta and now its like 60% arg for 40% bra that go there every year. It used to have an european vibe, with the constructions (i.e. the Cine Lido or the San Rafael casino) and all; there was an International film festival, Sofia Loren and all that kind of stars used to go every year, and now it turned into a Miami new rich plastic thing, although there are still some of the old people of old Punta going or living there.
One of the major changes obbeys to social segregation. Punta was although exclusive, traditionally an open space to everyone, people who went there had a big tradition with social integration, upper middle class proffesionals, etc, (this is the european thing I ment) but that changed all in the 90s when a lot of country clubs appeared, and with the Brazilians (where insecurity is totally another thing than in Arg and Uru) grew exponentially. Now is just another people, it is much more international, a paradise for cruises (which didnt exist til the 2000s) and bussinessmen, an enormous laundry machine, with horrible and tacky new towers -like Miami or Brazil-, since Uruguay dont have any law of asking where the money comes from (unike Arg and Bra).
It had lost its charm, it is another thing today.
Punta is totally decadent. People who used to go now are moving to Rocha (La Pedrera, etc) because of its popularity, celebrities, fashion stuff and all this new target.
PS: my mother was born and raised in Punta, and I go there every single year of my life + I lived there for one year (2010), so I know what I m talking about.