It’s a terrible experience first for the writer and then for the reader. Thread Reader is meant to make things less miserable for readers, and to some degree it accomplishes that, but whenever someone sends me a thread — I would never choose to look at one — you know what I inevitably think? Lordy, this is badly written. See, Thread Reader can’t do anything to reverse the damage the 280-character limit inflicts on a person’s writing: such writing is invariably choppy, imprecise, abstract, syntactically naïve or incompetent, lacking in appropriate transitions — a total mess in every respect. (Some of this happens because the writers get distracted by comments that start coming in before they’ve finished the thread, but an undistracted threader is still a poor writer.)
Read his entire post at his blog, Snakes and Ladders.