If this listing is up, the item is still available. I will ignore all "Is this still available?" messages. Send your offer or time you would like to pick-up in the message.
And then I ignore all those other messages.But make no mistake, they don't care about your experience in the slightest.
The textbox and the button were always there to drive user engagement. Number go up!
Here's a likely bad parallel (well, maybe not so).
The "safety" on a Glock pistol is a little lever on the trigger itself. You squeeze and it unlocks, squeeze some more and it fires. In other words, it has no safety. A five year old can accidentally fire a Glock. On a normal firearm it's a little lever on the side that you have to rotate. Without that, the trigger does nothing.
This idea that users are "engaging" on FBM is just as fake as Glock saying they have a safety.
Weird parallel, I know. It's what came to mind because that's one of my all-time favorite stupid designs to point out.
Not genuine engagement, mind you, but measurable nonetheless.