I still don't understand those platforms. Didn't when Twitter launched and still don't now that there's several of them. Same thing for like Facebook or its predecessors. They're all more about the person than the message and I honestly quite frankly don't give a shit about random people on the internet.
Sometimes the identity of the messenger is important.
Twitter was super easy to set up with the API to periodically tweet the output of some automated script: a weather forecast, a public safety alert, an air quality alert, a traffic advisory, a sports score, a news headline, etc.
These are the types of messages that you'd want to subscribe to the actual identity, and maybe even be able to forward to others (aka retweeting) without compromising the identity verification inherent in the system.
Twitter was an important service, and that's why there are so many contenders trying to replace at least part of the experience.