1) The internet is directly and indirectly incentivizing this kind of attention seeking behavior. It's rewarding to be noticed, upvoted, and retweeted. Pleasant, well reasoned, and evenhanded discussion rarely gets as much attention as sassy clapbacks.
2) Younger generations have been raised to believe that activism is a virtue and that injecting politics into everything is the way to affect progress (intersectionality).
3) Young people tend to be more vocal and more prolific. This is probably because they have more energy and free time than older folks. Additionally, young people tend to be more abrasive/obnoxious, as they don't have as much life experience to tone themselves down and learn how to behave.