"People are being funneled into "ideological bubbles""
I'm not as convinced they are being funneled. I remember back in high school, my friends and I would sit around in a circle, in meat space.
"War is wrong"
And we would go around the circle: "yup", "absolutely", etc
"Some other liberal talking point"
yup, of course, so true....
I feel they are self selecting. Look at the election, when liberals were 3x more likely to unfriend people. [1] And I think they have been self selecting since before the internet. Also there is a geographic component. Rural areas vote red, urban vote blue. We have had geographic filter bubbles for decades.