(CNN) -- Perhaps the blog VentureBeat put it best: "Twitter appears to have a problem sharing friends."
Twitter on Wednesday pulled access to a friend-finding feature that let Tumblr users search for contacts on Twitter who also use that blogging platform, Tumblr said in a statement. Tumblr users still can find friends using Facebook and Google.
It's just the latest news in the saga concerning what critics say is Twitter's inability to play nice with its friends on the Internet. The social platform, once known for its openness, has been putting up walls around its service to make it more difficult for other sites and apps to access its data.
Twitter largely has been mum on its motives for these changes, but some people have defended the company, saying it has to take control of its data to turn a profit.
"I don't think people understand that Twitter is a start-up that has to make money, not a non-profit-up," New York Times writer Nick Bilton said on Twitter.
Tumblr is not happy about the most recent change.
"To our dismay, Twitter has restricted our users' ability to 'Find Twitter Friends' on Tumblr," a spokeswoman said in a statement. "Given our history of embracing their platform, this is especially upsetting.
"Our syndication feature is responsible for hundreds of millions of tweets, and we eagerly enabled Twitter Cards across 70 million blogs and 30 billion posts as one of Twitter's first partners. While we're delighted by the response to our integrations with Facebook and Gmail, we are truly disappointed by Twitter's decision."
In July, Twitter revoked friend-finding access to the photo-sharing app Instagram, which is owned by Facebook. And it restricted the professional network LinkedIn, too.
"Consistent with Twitter's evolving platform efforts, Tweets will no longer be displayed on LinkedIn starting later today," LinkedIn wrote in June blog post. "We know many of you value Twitter as an additional way to broadcast professional content beyond your LinkedIn connections. Moving forward, you will still be able to share your updates with your Twitter audience by posting them on LinkedIn."
Twitter also announced changes last week to some of the rules governing the way it shares data about its users with other sites. They go into effect in six months.
The company, which acquired Tumblr's competitor, Posterous, in March, issued the following statement to CNN via e-mail: "Some folks covering this have pointed to our comment from the Instagram situation. ('We understand that there's great value associated with Twitter's follow graph data, and we can confirm that it is no longer available within Instagram.') We don't have anything to share beyond that."
Twitter's recent moves have been met with considerable criticism.
"This reeks of grade-school drama," Jennifer Van Grove of VentureBeat wrote in reference to the Tumblr friend-finder change. "It's the second instance of Twitter acting like a bully and refusing to share its friends on the social networking playground."
Matt Buchanan, the BuzzFeed writer who predicted that Twitter would block Tumblr's friend-find feature, writes that all of these changes are confusing for developers of Twitter apps. Twitter increasingly sees these apps as competition, he writes.
"It's easy enough to say that the One Rule to Rule Them All is, 'Don't compete with Twitter.' Which is fine and dandy, because it's all for the greater good of Twitter or whatever. The problem is that it's real easy to be a valuable, contributing member of the ecosystem today and then tomorrow find out that you're now competition waiting to be crushed."
The Next Web said, "This is part of Twitter turning the screws on sharing information about the users of its network."