Twitter created a bit of a stir late last week by cutting off LinkedIn. Ostensibly this was to project a consistent look and feel for tweets as the company adds features like threaded conversations, which LinkedIn didn’t convey. People who have accounts on both services will no longer have their tweets appear on their LinkedIn profile pages. It’s hard to know how much these updates will be missed on the business-minded network, which distinguishes itself by hosting a more focused conversation than “anything goes” Twitter. But the practical effect is that if you want to be heard in both places you’ll have to repeat yourself, unless you choose to do all your updates from LinkedIn, which still feeds one way to Twitter. More likely, you won’t because it’s too much of a bother.

Bad for LinkedIn. Much worse for Twitter.

Twitter’s ability to pipe in to other networks is a big reason for its popularity, and in doing so it has aggrandized other networks. All this has been, to the outside observer, symbiotic: People like to share their tweets everywhere they hang out; networks benefit from all that chatter and Twitter gets its hooks into everything.

In cutting off LinkedIn, Twitter doesn’t seem to be adopting the “first taste is free” business model it has previously practiced. That’s what creates addicts who can then be charged through the nose. Now Twitter seems to be calculating that isolationism is a shrewd business strategy, that it has less to lose by pulling back on sharing agreements than the networks it drops.

I think this is a path to ruin. As I tweeted (of course) after the LinkedIn news: “Twitter’s value is its integration with other networks. Cutting them off is like being on the wrong side of history.”

It wasn’t the first time Twitter had alienated collaborators in a bid to hone its destiny. When it acquired Tweetie two years ago, Twitter absorbed one of its most popular third-party clients. Third-party developers – as Tweetie’s Loren Brichter had been – were chilled. They realized that their free reign was temporary. They helped give Twitter access to a huge pool of customers, but Twitter always held the power.