Another word for an echo chamber, or something that returns something too similar to what you type or say.
Literally works by probability and semantic distances. Especially if what you write is not a question.
Yes, it's more profitable than sending random content.
Most friends are like this by nature. Because otherwise it would be stranger and stranger; that's where the word "stranger' comes from. Strange to you because it does not mirror enough of your beliefs.
Obviously, on a basic level, if you found something/someone totally against your culture, or even a different language, you would be skeptical. However, the best way to expand tone concept network is by similar not same stuff. On the other hand, a bubble just repeats what you know.