“Inception” is frequently misunderstood to mean entering other people’s dreams or having multiple layers of dreams.

In the movie, they of course have the technology to do these things, but it’s usually used for “extraction”: stealing information and ideas from one’s subconscious by infiltrating their dreams.

“Inception”, as used in the movie, is just the opposite of “extraction”: to plant an idea in someone’s subconscious by infiltrating their dreams.

So while I think it’s a stretch, it’s not as bad as suggesting that people can commingle in dreams.