Facebook - why do some people refuse to use the "reply" feature when replying to comments?

[­­­­ㅤㅤ]

On most pages, they have the replies to comments turned on in their post but some people don't use that feature. Here's what I'm talking about:

Person A writes a comment.
Person B correctly replies to the comment.
Person A replies back, but not as another reply, but as a totally new comment.
Person B correctly replies to the comment.
And the cycle continues.

Instead of keeping a conversation within the replies of the first comment, the conversation gets scattered along many comments making things hard to follow. So why do people refuse to use the "reply" feature?

[john]

Those bastards are a plague upon our society.