They severely limited the amount of requests per minute (for example you can only reload your timeline 15 times every 15 minutes). They have also refused to open up the API endpoints that would allow those 3rd party apps to have a functionality on par with the official clients. They also limited the number of authenticated accounts under one app to 100,000, a limit which has been hit by some clients already.

That said it must be understood that tweetbot is probably the only worthy 3rd party client as of now. There are lots of Android clients but they are all of a very low quality. Whether this is because of the lack of incentives to build an app that uses an API that could close at any moment, or just reveals how bad Android apps are overall, remains to be seen.

Four years ago or so I used twicca, which was pretty good at that moment, but it hasn't been updated since then.

According to Ryan Sarver, former Twitter Platform Director:

"Developers ask us if they should build client apps that mimic or reproduce the mainstream Twitter consumer client experience. The answer is no." "We need to move to a less fragmented world, where every user can experience Twitter in a consistent way."

https://groups.google.com/forum/#!msg/twitter-development-ta...