One way to mitigate that problem is to make messages cheaper to listen to, and broadcasters cheaper to find and follow. In a medium more carefully optimized for listeners, audience sizes will be sufficiently improved to make it worth the extra effort demanded of broadcasters.
The result is a new kind of broadcast channel: one in which broadcasters don't need to invest millions of dollars into to overcome the cost of acquiring listeners (like television, or even news websites), so many many more broadcasters can profitably use it; a virtuous cycle ensues where more listeners are attracted, attracting more broadcasters, and on and on.
I don't think that was the original thesis of the site (original thesis: "users will enjoy a site that lets them tell their friends what they're doing right now"), but I do think that's where the value turns out to be.
OK, yes, you can pretty much always twist and manipulate semantics and express anything in terms of a "pain", but is something getting lost in translation? I don't have the answer, but I think it's worth thinking about.
"What problem does your startup solve"? Important question, no doubt. But if you go back to the "vitamin or painkiller" analogy, sometimes it's OK to be the vitamin. And sometimes something becomes popular just because it's fun and novel.
All of that said, what made Twitter so interesting? I think originally it was the idea of a "near real time" way of distributing messages to a group, coupled with the knowledge that A. the messages you receive would be short, so you could parse them quickly, and B. the messages you would be composing would be limited, which meant that tweeting couldn't turn into too much work, the way writing a blog post might.
(Though if you're asking about the historical pitch, I believe it was originally about having a blog that people could follow on a dumbphone)
Thinking about it more though, I would say that Twitter should not be compared to blogs. I think Twitter is more like IRC. Twitter is a simpler version of IRC for the masses that can be used via dumb phones. Add in hash tags, search and an easy to use filtering system, and Twitter actually seems pretty good.
I'm going to NYC for the first time this week. I want to eat at places where the locals eat, not what's trendy on the Web or TV. How did I get recommendations?
Twitter.
I reached out to NY food bloggers and they happily responded with tips.
I don't need to get introduced by someone else. I don't need to personally know them or "friend them". I don't need to pay for 3rd party services to hunt down a phone number or an email address.
People often miss on what I think is one of the most fantastic features of Twitter.
It's a good way of broadcasting news in realtime.