This is already happening to HN as tech people flee Reddit.
Most of the new comments on any given post are people that didn't read the linked content and complain about stuff addressed in the second paragraph.
This is an evolutionary process where the commenters that get the most engagement are those that are first to respond or react. First-mover advantage entrenches itself as those posts are boosted higher due to the engagement they receive.
Those that think deeply before responding are discouraged when a well-thought out comment is buried beneath a sea of first impressions.
This reward cycle is amplified by more people, because engagement is very unequal on platforms that share a top comment or front page for everyone. You either make it to the first few comments or get nothing at all.
Sites like Discord or Facebook try to counteract the monopolization of engagement by an impulsive few by splitting users into smaller groups. Less competition for social interaction creates more diversity in winning strategies. Evolutionary pressures still exist, but you don't need to perfect a "winning strategy" solely to interact with other people on the platform.
Contrast Reddit or YouTube videos. The concentration of attention means it has monetary value due to SEO, product reviews, or advertising. The value of a large audience makes a platform more competitive. Competitiveness means many YouTubers and Redditors professionalize attention-seeking behaviour. This comes at the cost of quality.