Twitter wasn't ever really a new protocol in the same way as the others, as it was owned entirely by a private company.
Protocols are open standards that anyone can implement and use without needing permission from or reliance on a single entity. Twitter, by contrast, has always been a proprietary platform, entirely controlled by a private company, which fundamentally undermines the comparison.
Most of the challenges Twitter has comes from not actually being a protocol. If Twitter had been designed or evolved as a decentralized protocol, it would have avoided many of the issues it faces today.
Protocols are open standards that anyone can implement and use without needing permission from or reliance on a single entity. Twitter, by contrast, has always been a proprietary platform, entirely controlled by a private company, which fundamentally undermines the comparison.
Most of the challenges Twitter has comes from not actually being a protocol. If Twitter had been designed or evolved as a decentralized protocol, it would have avoided many of the issues it faces today.