Getting emails from a random guy in your old contacts list with an empty subject and just a single random link is one thing... But wtf, steam friends? ;-;
I never got something like that...
What I DID get however was some guy who somehow got on my friendslist, then disguised himself as someone else on my friendslist and tried to make me download some crap and "test it because it wasn't working for him".
But yeah, you can't get a virus from simply accepting someone on your friends list, lol.
And even if you could, I'm not accepting anyone unless I really know the guy anyway. Because I get countless invites every week (probably from HRP players) and my friendslist would be full within no time if I really had to accept all of them. Not to mention 9 out of 10 times they only add me so they can annoy me about HRP stuff that you can just as easily use the report feature for.