"feel the need to defend their polarized but flawed viewpoint at any cost" usually results when people want [extreme] attention in a sea of chatter.
"are virtue signaling others but refuse to take any accountability whatsoever" a tactic typically used when people want [extreme] attention in a sea of chatter.
"have less and less attention span" Time is money, and it's better to waste your time reading/bickering about your tweet for ads that wasting time writing a meaningful tweet that'll be obsolete in 10min.
"only consume the content that aligns with their views" usually results when people want [extreme] attention and creates an echo chamber.
Conclusion: we got a lot of narcissistic people on twitter. The ultimate digital soapbox.