This sort of thing has been an ongoing problem for many years in Europe, not just in Paris.

Twenty years or so ago one of my traveling companions was attacked by a group of kids by the Louvre who waived signs and maps in her face while yelling at her. When they ran off she found her wallet and watch were gone, too. The Paris Police could be barely bothered to take a report (filled out on a very old manual typewriter at the station) although with the report insurance covered the loss.

And, I had much the same thing happen to me in Barcelona a couple of years ago, although I got away with no losses. I was told then at Catalan law is not effective if less than five hundred Euros or so is stolen and so the cops do nothing about these things which have become more common since the borders in the EU were opened.

The whole thing is very odd to me because, usually, French law enforcement is pretty good.