1. The person looking at a profile is not a paying member, so they canNOT send messages.
2. They are just looking around.
There are MANY other possible reasons:
1. They MAY be rude, but...
2. They may be SHY.
3. They may get busy and not check their messages for months.
4. They may become ill or injured or get a new job or get a new grandchild or.....
5. They may not know HOW to send messages back to you.
6. Their subscription may run out, and that's why their profile is unavailable. Is that "rude?" I don't think so.
What I mean is: I hope you (we!) won't get discouraged by WHAT IS NOT, but rather rejoice in all the good things and good people we find here. :)