I’m no watch expert but I can google stuff, and apparently the Oyster Perpetual series was introduced back in the 1940s. It is a classic Rolex design that has kept its relatively small case diameter through the decades (although it has varied somewhat). We are currently in an era of absurdly huge watches. So an Oyster Perpetual of ‘90s vintage will look appropriate — in a relative way — on a woman these days. That may be a factor in your female friend’s interest in the watch. I will add that the pendulum seems to have begun swinging back towards more normal watches sizes.
Agreed, I see watches that are huge. To each his own, but I would not wear watches so large. It draws attention away from the rest of the wardrobe.