Yes, I'm one of those people who probably respond once or twice, but let things be as they are as soon as the conversation about the topic at hand is finished. As a matter of fact you and I exchanged some friendly messages about a year ago (I had to look that up though).
It's not malice, it's my way of being. I don't feel a need to expand my circle of friends (mind you: I basically have none...just some left over JW semi-lost friends, and two old jw now exjw friends with whom I must push myself to rebuild the friendship), nor do I (claim to) have the time to.
In fact, I strongly believe being raised as a JW is a root cause for this behaviour. Being raised as a JW you'll have insta-friends wherever you go. You'll never learn to properly start and maintain friendships.
Others here simply move on; some members whom I had pm contact with here appear to be gone from this forum.