Discussions

I am curious how many people actually do this and why they do.  
 
Example: I would run out of fingers if I used them to count how many private messages, emails and even form submissions from my website from people who have taken exception to my comments on an internet forum (not just E-Brandon) and feel like they have to inform me that they either don't like me, that they feel I should not be so outspoken or opinionated and even have had threats made aginst my business etc. In the last couple of weeks I even had someone 'reearch me' and inform me that they know all about me.  
 
Now personally I don't care because I have never hidden behind an anonymous screen name or said anything I wouldn't stand up and say in person during a similar discussion face to face. Internet discussion are just that to me - discussions on topics, they are not personal. I have never looked up someone who disagrees with me or anything like that but I am wondering how many people do?  
 
Do you? If you do - why? If they don't agree with you or you don't like what they say in a discussion, what do you hope to gain by going behind the scene and scoping them out? Is it a form of intimidation? Online bullying?  
 
I am not talking about discussing things in a PM, I mean going beyond that and making it personal.  
 
Thoughts?