Benefits of being someone's colleague on BP

[Account Closed]

I normally love getting a colleague request, with a message from the person who wants to add me as a colleague.  I find it really fun and flattering and I enjoy the back and forth messaging.

But, occasionally I'll get a colleague request with no message at all.  So, I'm wondering what the benefit to that person would be as my colleague?  They don't want a discussion, so what do they want?  

Does being a colleague allow someone to know something about me or follow my posts or something?  I'm not a facebook person, so I'd guess it's similar, but I just don't understand why someone would ask to be a colleague, but not also touch base with a message.

Can anyone explain this to a non-facebook type person?