Initially, it was a way for me to bond with some of now longest friends. I can't remember if they showed it to me in 7th grade, or if I found it myself and we all happened to play. I also had a pretty close online friend I'd play with it a lot, but thinking back on that relationship, they deceived me in a completely unbelievable way in retrospect. I don't even remember how I stopped talking to them, but it's probably a good thing I did. I think I was just lonely haha. In terms of the actual game, it was my first MMO, so being able to just run around in this huge area with random content was crazy. The F2P area is nothing looking back now, but it felt MASSIVE as a kid. Eventually I was able to get a membership, and that actually has a lot of content. The quests were actually engaging compared to most of WoW's style of quests where you kill 10 boars or get a random item with a .01% drop chance. Some of the puzzles would have been impossible to figure out without a guide.
I would later give it up to play an infinite amount of other MMOs. I had a core group of friends in middle and high school, but I was terminally online from an early age, so I had a lot of online friends too. A few of us just loved playing f2p games from Asia. I haven't talked to any of them in years, though...
I've jumped into the old school Runescape re-release a few times when I feel like I don't have much going on. It's something to mindlessly pay attention to when nobody is up to do some multiplayer. Thankfully, I haven't really needed that recently. It's kind of cool being able to accomplish all the stuff I wanted to as a kid. There's not really a social element to it these days, though. You can definitely sense an age difference.