Social media are not the internet. If Facebook, Instagram and tiktok disappeared tomorrow, the internet would keep existing. In my opinion we would all be better, queer kids included.
From a teenager's perspective, Instagram and TikTok are a lot worse for your mental health than say, Snapchat and iMessage.
In addition, for the queer community example - I'd say the perfect parallel for today would be Discord. Anyone can find a community and make friends on Discord, but it's probably not 5% as damaging to mental health because it's a communication based platform
I was on the internet communicating with friends and strangers on forums/message boards, IRC, AIM, and pre-feed Facebook well before the news feed was the default model. The "stalker feed", as it was known in 2006(?) when it was first launched, totally changed things, both in terms of the volume and ease of scrolling through content and the kinds of "news" that would be brought to your attention.
Something that sticks out in my memory of when Facebook's feed launched (I was in college at the time) was the additional pressure surrounding the "relationship status" field. Suddenly it wasn't just people who actively looked up your profile who might notice that you were "In a relationship with X", instead the act of updating it was broadcast to hundreds of people. Low stakes for adults, perhaps, but genuinely stressful for teenagers!