The distinction that the text box is at the bottom of the discussion is no different than “comment box at the end of a New York Times article”, and we all know how that story goes… we’re advocates for thoughtful friction:
And, we are on the verge of shipping built in chat, so you can switch from the slow lane to the fast lane if you want to brainstorm and have a rapid back-and-forth conversation that won’t end up immortalized in Google’s index for the rest of time. It is possible to have your 
and eat it, too.
Heck, sometimes you want conversations to go on for years, like this one… 