Galaxy
I am more frightened of social media giants having more control over speech than a few ignorant racists. Imagine if trump owned a social media platform, would you be happy to have him control speech. I agree with Laura it's about education and an ongoing discussion about social media and what it is or isnt doing for our society.
This is the thing, isn't it?
If everyone were identifiable online, dictatorships would crush dissent, as they do in China and Saudi etc. Look at that case a few years ago when a man was sentenced to 1000 lashes for starting a blog.
Also, if the authorities could identify people, it would be a short step to extremists being able to do so too, and they could threaten anyone who spoke out against them. It's not straightforward at all.
I think that we should look at ways of making racism unacceptable (as happened with drink-driving and smoking indoors), so that people wouldn't want to post their bile. I know that racism is more ingrained than either of those examples, but if there were a will I think it could be done.