This never has any numbers to support it, which is unfortunate.

Also, in a world of bubbles, how is a less free an open Twitter better? Is a Twitter with no controversy, with no argy bargy, really worth visiting?

I think Twitter's problem with trolls is minuscule compared to the problem of making it more entertaining, and easier to switch in and out of thoughts. If I like the NBA, cricket and South African politics, how do I switch between those three interests when, say, there is an NBA finals and a local election on? That is a problem much more so than trolls.