We can see lots of useful examples of a protective social norms with alcohol. For example, it’s quite common for people to not drink any alcohol before a certain hour of the day. It’s not illegal to drink alcohol earlier, but it’s “just not done”. We can easily see the benefits of not drinking at the start of the workday.
I’m not going to guess what kind of social media norms people are developing in general. For me I only follow boring, topic-focused people on Twitter, and I only use the “Following” feed. Nobody is making me do this.