Yeah, I’m betting you all got one from the same one… 
I’ve been adding to it for the better part of the last five years or so. At first it was just posters whom I really like and enjoy posts by and usually find myself agreeing with, but lately it’s been posters who I recognize the names of and think or know of as a “good, regular poster” who is a nice addiction to this message board community.
Or, as I put it to someone recently, in a PM, who asked me about it it:
“I started wanting to add the people whose named I recognized. I went from first (and for a long time) just adding those posters I REALLY liked and loved most posts by…but over time I have expanded it to include more and more just posters whose names I see all the time and know/think of as “good posters”. Ones that I see so much and often that I almost start thinking of them as old friends…even if you’ve never even talked to them. You know how it is? You might see a certain stranger every day and, even though you’ve never really talked to them, maybe you smile at them in passing or say “hi” every day as you walk by…and yet, you know nothing about them beyond that…
…but over time, years of doing this, they become like “good people” in your mind. To where you’d notice if they were gone maybe. That’s what a lot of the people I’ve been adding has been like recently”
I also tend to have my contact list on here open at all times, in the background…and when you have people added, it updates automatically, having their names appear (in red and at the very top for the first minute) whenever they first log on and then their name sticks around on it until they either log off or are idle for about fifteen minutes. So I find watching the comings and goings of most of the regular, long-time posters passes the time nicely and is strangely cool to watch while I’m doing other online things (like watching videos or playing games, etc).
It’s also oddly comforting. I suffer from anxiety attacks sometimes, especially in the middle of the night, so sometimes I’ll just click the contact list and watch the comings and goings of people who are on late at night or middle of the night for me. Just knowing or seeing people whom I know or interact are currently online is a little cozy and calming somewhat. Like people keeping watch or vigil at all hours or who “leave the light on”.
Yeah. Weird. And possibly creepy-sounding. But it helps and, like I said, oftentimes relaxing.
Best thing is, adding someone to your contacts list on here doesn’t require you to accept them. If you deny the invitation, that person won’t show up as a “friend” to you on your profile, but you will still be added to the person’s list who added you regardless.
Other ways it can be used (and that I use it) is to help me find the posts of those posters I enjoy the most and like reading topics by and to find posters to PM them fast if need be or if I want to…
…and many posters can attest to me PMing them. Trust me. I am known for randomly PMing people to see and ask how they’re doing or to hopefully put a smile on their face or show them that they’re noticed and liked. I think I PM three or four posters a day, and usually ask how they’re doing, but sometimes will crack a joke or two about their screen name or comment about a post or topic they’ve made in the past and tell them how much I agreed with it.
Anyway. That’s the mystery behind my friend request if you have ever gotten one from me on here.