Plus, the development of any given 'pivot' is not necessarily trivial, and could be beyond the skills/resources of a company/person to do so.
it was an incredibly popular live streaming app that died after the skype purchase. Sadly we all seem to have short memories. It offered everything you state. Again nothing new is new.
1. Write thousands of words of text in an HN comment
2. Be accused of failing to mention one of the dozen livestreaming apps?
But beyond that, it took the iPhone (and devices like it -- but really, let's admit it was the iPhone. I loved my Treo, BlackBerry and Windows Mobile devices too, but it was the damn iPhone) to usher in a device where people could stream on the go. Before that, using Rhapsody (or even Spotify, early on) was kind of a PITA.
Spotify made it easier by letting you sync offline stuff with your iPod or iPhone, but it took widespread 3G and beyond, good data plans and saturation of smartphones for people to be like, "yeah, I can replace my iTunes with streaming music."
The same is, to me, true of streaming video. You could do live streaming close to a decade ago. On your cellphone. Shit, I remember envying people using Qik on the Nokia phones in 2008. But it took a long time, there was massive latency and the quality sucked.
Meerkat and Periscope are fast, easy to use, have restreaming features and are easy to drop-in, drop-out of.
Whether they last or not, I don't know. But just as it took e-sports to make the Justin.tv model work (and I remember when they launched Twitch. All of us, myself included, thought it wouldn't work. But then the devices for livestreaming game videos became so inexpensive and the experience so compelling, Sony and Microsoft built it into consoles. It took the barrier getting super easy and the content being compelling for the user case to be seen).
So again, timing.
Video game live broadcasting existed as early as 2005 from Korea, where we would get a 240p stream from OGN (a Korean cable channel), which would sometimes get replicated over users' personal servers. Only the most hardcore Starcraft Broodwar fans stayed up until 3am to watch these games live though.
And its a niche, but it's in a sense, a way more accessible niche than watching a random person lifecast. You're watching someone game. Which isn't that different from watching people play sports on TV.
To cite classic example, their were plenty of smartphones before the iPhone but the iPhone was still "revolutionary".
The same thing happened with publishing text (handwritten HTML to CMS to blog to Twitter). Each step opens the task to a wider audience it was previously inaccessible to.
[1]http://techcrunch.com/2007/10/15/justintv-lifecasters-not-we...