Depends on what you are referring to as 'personal information,' I suppose. Information related to dogs, or personal info outside of dogs, like family, jobs, etc? Also depends on the topic of conversation I guess.
In general, I only give personal info that I don't mind others knowing. As you said, this is the internet and anyone could come in here and read it.
I don't really think people are treated rudely because they don't tell their life story. I am sorry if this has happened to you.