Now, the issue of the improvement of the audience-protection tools has to be understood in the context of the users priorities. If you, as an audience member, can ensure that the users' fake news and troll/sockpuppet armies don't pervade your timeline, then the service becomes distinctly less valuable to the users.
What twitter is selling is eyeballs, what they need to do is to guarantee delivery of those eyeballs to the users. If that contract is broken, then no service can be given.
This runs into the last of my theories - the whole free speech thang.
// @skematica @kdfrawg