Places like Paris are simply overrun. It's not about the phones. It's about the hordes of people dominating the place. Same with most European capitals. They've become 'unlivable' cities. And, of course, any of us visiting any of those places for pleasure is part of the problem.
If you stand in the back of the perpetual crowd surrounding Mona Lisa, you're part of that crowd. Is it good? Is it bad? The punters bring in the money that hopefully pays for a some decent security so the next batch of artworks isn't stolen, or that allows other works of art to be preserved in a durable manner. At the same time, the city center of Paris has become a terrible place to spend time at due to the hordes of Chinese, Americans etc.
No different than when the French, Germans, Brits, Japanese et all come to the big North American cities on holidays. Big cities are crowded to begin with and adding visitors in large numbers as happens in the summer, especially, just make them moreso. It's not a uniquely European or British or Asian or ... phenomenon.
Tourism, by its nature, encourages "the hordes". The destinations promote it because tourists are a significant source of revenue.
But there's a more fundamental question here. Why do we look down our noses at the phone snappers who often do not see what they're looking at? We Elite Photographers (tm) who drag a bunch of equipment around to "properly" photograph a destination can be seen doing much the same thing. I have seen all manner of people dragging around Nikon, Canon, and Leica kit just banging out pictures and clearly disconnected from the actual experience of it all.
I was quite fortunate. For some decades, my global trips were part of my jobs and I thus got to know some of the people and experience some of the culture. I used my downtime to photograph these places and thereby felt a lot more connected to the whole experience. These days, I find myself spending more time looking at things when I travel than I do photographing them. The photographs I do take are therefore much more considered.
I will stipulate that people who grew up in the all digital age tend, in my observation at least, to have much shorter attention spans and tend not to concentrate a lot on any one thing for very long. But that may be confirmation bias on my part. After all, I have now lived long enough to be entitled to say "These kids, these days ..."