1. Marco Arment writes about Twitter's limits on developers. "Even though we don't currently have a Windows 8 client, we might have one in the future, so yours isn't allowed," he paraphrases on Twitter's behalf.
2. Bijan Sabet, an early investor in Twitter, posts two pictures. One when the company had 15 employees and a wide-open API. That was just four years ago. And the picture from today, when the company has 1500 employees and doesn't allow developers to compete with them.
Now I don't know for sure why Twitter changed their policies, but I can take a guess.
Those 1500 employees have to do something. At least some of them are going to write the clients that the developers used to write.
Which raises the next question. Why does the company need to hire all those people to work for money and stock when the developers are willing to do it for love? When you have the answer, you'll understand why Microsoft has shipped so many new versions of Windows over the last ten years, when the market was perfectly happy with the version they produced ten years ago.
Spoiler: All those employees make decisions that tend to keep them employed. That's how small innovative companies become big incumbent ones.