Near a small town there was a small lake. Many people loved to swim in the lake. One year, a terrible accident resulted in harmful pollution spilling into the lake. No one swims in the lake anymore.
They haven't stopped swimming because of some better alternative. They stopped swimming because swimming conditions have changed and now it is a bad idea.
If section 230 is repealed and social media becomes too toxic for most people to use, of course people would not stop communicating. The vast majority of human communication doesn't even occur on social media.