True enough, but modern tires (Vredestein Sprint Classics come to mind) may be built to conform to vintage sizes but are a vastly better tire than what we drove on back in the day. My Super came equipped with 165x14 Vreds which were H rated and were superb ties in all respects. Likewise, the Avon CRZ66 rally tire I'm told is an excellent H rated tire in 185x70x14 and other sizes. My Super's currently driving on some H rated 185x65x15 Kuhmos which, although amazingly cheap (I think I paid $55US ea.) compared to Vreds or Avons, turned out to be quite good tires.Tire choice is not simply a matter of buying replicas of 1960's and 1970's tires. Things have changed for the better. Tires are now demonstrably safer, grippier and often more durable and puncture resistant than 40 years ago.
Unless you are seeking a car that is in essence a museum piece then some consideration of the type of tire you need is very important.
It also worth considering that modern high performance tires, in addition to coming in relatively smaller aspect ratios, are also intended for very different suspensions than our old vintage Alfas have. Most Alfa suspension modifications use uprated springs, shocks, and sway-bars which tend stiffen the overall ride. It's acceptable with taller aspect ratio tires (I chose 65 aspect ratio tires for a reason) but become harsh with most low aspect ratio modern performance tires. (I also think those tires look dumb on old Alfas, but that's just me).
Finally, modern tires in vintage sizes aren't really "replicas" of vintage tires. They may look vintage but modern Centuratos or Michelen XAS's may look vintage but are constructed according to modern designs and manufacturing techniques.