Any single given application on Ethereum (except straight-up value transfer as seen in Bitcoin) isn't compelling enough to have its own network, but together they are.
I have never seen that file extension before, but the language looks to be C-derived.
Please note there's a donation mechanism .
If others like what you write, there's a chance you can get back some of the money you spent on tweeting ;)
Still, using blockchain technology has positive aspects, like some kind of censorship resistance. That is, if some country is going to block access to Twitter again: who knows, can this be an alternative? Not saying access to the ethereum network can't be blocked at all, though.