I think you are right that some GNs do seem to talk about their own lives quite a lot but perhaps this is the only place they can do so. If it helps them then it is a good thing. Some of us prefer to keep the more personal stuff private. Each to her own.
It is different if they are just saying a little bit in order to show that they really do understand what someone else is going through though.
When you chat in real life to a neighbour, you discuss all kinds of things, but the longest talks are about yourselves and what is happening to you and your families.
I'm not sure that is exactly how it works and I certainly don't think it is sad. Rather it's fascinating, revealing, reassuring, infuriating, touching and many other things.
Have you noticed that the threads that go on for the longest time and get the most posts, are the threads when gransnetters are talking about themselves?