It's not derived from that. Most people don't use IRC anymore and there are basically no open chat platforms left. Most people now use phones to chat, where the

It's not derived from that. Most people don't use IRC anymore and there are basically no open chat platforms left. Most people now use phones to chat, where the keyboard automatically changes case for you after finishing a sentence. So typing in all lowercase is a choice. I think it's a way to signal "I don't follow norms". It signals membership in a group.