Intro
When I introduce you I am putting myself on the line. I'm putting the trust and relationship that I have and taking a slice to hand over. It's not nothing.
While most times it isn't a big deal, this is why it is often met with reluctance. Beyond that, you become a third party involved in whatever ensues, which you get little credit for if it works out, but lots of credit for if it doesn't.
I wonder if people realize this, or if they remain unware. I wonder if I'd want to be someone who cautiously asks for intros or instead asks as if there is no harm.