I think Twitter's issue is a vision problem, they don't have a good idea of what they're trying to do.
Facebook's is trying to connect the world - this leads to FB messenger, Oculus, Instagram, trying to buy Snapchat, internet.org - basically acquiring or creating what they can to drive human interaction and communication online.
Twitter has one thing they built that they've made awkward changes to which most people seem not to care about. Closing their open APIs which built on Twitters core value was a mistake and their attempts to monetize in weird ways at the cost of their own usefulness has also not worked out.
I would say the mission of Twitter seems to be "help people promote their personal brand". Unfortunately for them, not everyone is interested in either doing that or reading about other people doing it.
Facebook's is trying to connect the world - this leads to FB messenger, Oculus, Instagram, trying to buy Snapchat, internet.org - basically acquiring or creating what they can to drive human interaction and communication online.
Twitter has one thing they built that they've made awkward changes to which most people seem not to care about. Closing their open APIs which built on Twitters core value was a mistake and their attempts to monetize in weird ways at the cost of their own usefulness has also not worked out.