I assume the fear was girls would sexualize themselves because of what they saw was popular on MTV, which they believed would make them popular as well. I guess the big difference is that girls that sexualized themselves at that time never had an access to large audiences without perceived consequences like girls do on social media today.
I don't think depicting violence in video games is similar because I would say the violent aspect of games isn't the defining aspect of the content that people want to emulate. For example all the video game streamers and influencers, like girls who sexualize themselves, generally want the popularity, and the popularity is derived from being good at the games (or being the entertainer), not by being violent or emulating the violence from games, whereas the popularity of sex symbols is inherently their sexuality. It was starting with internet chat rooms, but there was really no way to broadcast your sexuality to thousands of people back then without exposing yourself to risks like doing it in the public. Social media both removed these risks by creating a physical separation between the audience and the person sexualizing themselves, and provided an audience that provides the attention that those sexualizing themselves desire. It sort of created the missing pieces for the incentive structures that reinforce the behaviors.
It isn't just sexualization too, social media has allowed many communities that were either too niche or 'undesirable' to thrive in offline communities to flourish and become normalized over time.