Earlier quoted context omitted.
Every business is built on other businesses. In the 1800s if you wanted distribution you had to play ball with the railroad barons. This is just the 21st century equivalent. Likewise, if you're building a destination website you're dependent on Google, email spam lists (don't get blacklisted!), browser vendors (MSFT and ESPN once conspired to make espn.com for IE-only), and even ISPs (see: Net Neutrality). The risks…
There is a difference between those early dependence and Twitter. Twitter is still young, it's uncertain, and worst it's future is really unpredictable because it doesn't even have a business model to generate revenue yet. Building on top of a business is sensible when you are depending on something that's been there for a while, know it's dependable and have a reputation. This twitter does not have. If the same serv…
That's why he's so upset that Twitter cut him off.
So, yes, building on Twitter is riskier. Building on Facebook is riskier. But as distribution channels they have huge upside.
If the risk is too high don't build and wait for the channels to become more mature.