Meditation is a tribal act in a screentime age: quietly facing the same direction, obeying a common leader - together. Just like yoga, dancing, climbing & hiking.
I think tribal socialization is a better explanation for meditation's growing popularity than “watching your thoughts like a river.”
What you are describing is the "Westernized version" of Yoga. The Yoga practiced over thousands of years in India did not involve "obeying" a common leader except for the few months that you spent learning it. There was nothing tribal about Yoga. Far from it. Most Yogis would retire to forests or caves in Himalayas to practice Yoga in "solitude". And when Yoga was done for extended periods of time (months if not for years) it was called Tapasya. None of this applies to the commercialized Yoga that is practiced in the West. It was especially not for "freeing your mind" or "mindfulness" or "for calming your nerves" or "fixing an ailment". Those were side effects. The real goal of Yoga was achieving Moksha.
Do any of the centers/groups you have seen ever advertise that Yoga is for achieving Moksha? Never. That would defeat the purpose of commercialization.
I think tribal socialization is a better explanation for meditation's growing popularity than “watching your thoughts like a river.”