Many people can't go into long conversations about each other simply because answering requires more than one click. Even Google can't conceive of a better way of communication than Google Plus. I have to retype my answers to everyone around, whenever I get to meet a new person, I can't easily reuse my previous answers from an autosuggest list, and why not? Here is my idea, which I shared on halfbakery.com:
"Profiles should contain a 'magic FAQ.' Any vistor of your profile should be able to add a publicly invisible question to your magic FAQ; you would be notified, and have an option to answer it, both replying the questions and building your FAQ at the same time (one shot-two birds). The publicly invisible conversation could continue much like hierarchical comments, forming a hierarchy. The next time someone asks a similar question (i.e., adds a question to your FAQ), you could tell the system that it's just another way to ask the same thing, and reuse your previous answer with a click of a button. A different follow-up question? No problem -- the data structure like pHTN (probabilistic hierarchical task network, which is just hierarchically arranged lists with probabilities of each element in the lower level of the hierarchy) can handle this, and even learn to autosuggest you to reuse your most preferred answer (three birds?).
An expected result of this idea, is that even celebrities, who don't have enough time to chat with every fan, would suddenly have time to communicate personally, in this semi-automated manner."
I often feel guilty for ignoring other people's comments or questions, and frustrated when other people seem to be ignoring me. If I can't indicate to someone exactly why I'm not answering, or can't receive such an indication myself, I can at least help my future selves and others obtain a better probability distribution over such reasons. To that end, I'm listing all of the reasons I can think of for someone to not respond to a comment/question, to save the effort of regenerating these hypotheses from scratch each time and prevent the possibility of failing to consider the actual reason. Note that these are not meant to be mutually exclusive.
If I missed any reasons (that happen often enough to be worth including in this list), please give them in the comments. See also this related comment.