I'll be honest here (and odds are people are not going to like it. Oh well)
At 19 I sit roughly in the center of the age range of the people I've come to know on this game. The youngest was 11, the eldest is 30.
I feel like age does matter, in some circumstances at least. Now as Hugrf said, the game is 13 +. Personally? I think that is /great./ Now, yes, age limits did suck when I was younger but that was simply because I didn't see the point when I thought I was so much more "mature" than most of my peers. I'd blindly rant "not fair, not fair not fair!" until I was blue in the face. (speaking figuratively, mind you).
Now that Im older, I understand why age limits are set in place. It forces people to take responsibility for their behavior and I feel like 13 is a good age for this. Yes, most people would call 13 year olds "kids" and yes they're minors still in a lot of countries. But, the difference between a 13 year old, and say a 9 year old is that 13 is an age I think many can agree /should/ know the difference between right and wrong by then. You break a huge rule, you're warned, you do it again you get a huge ban, and you're not "let off the hook" because "you're just a little kid who didn't know any better." You're not a little kid anymore. You're 13. You should know by now. Yes, some 13 year olds are a little behind in the maturity power curve and some are further ahead but in the end, you being the one exception against the average does not matter when the mass majority aren't capable of handling themselves responsibly until that age. [and sometimes not until well after that!]
I'm sorry its a sad truth, no matter how "advanced, strong, mature, etc" you will always be forced to be looked as the average when viewed on a large scale/in a large population. Its easier to manage that way, and so people will almost always go about it that way and in the long-run, its usually better for everyone. Everyone else had to wait the same number of years to break that age limit, you don't get a free pass.
I've never felt like the internet was made for children, except for the specifically "child oriented" websites that parents should even still should be actively monitoring [or using time or computer parental controls to do so for them when they cant monitor them themselves] while they're online. Yes its a great resource. Yes it can be educational but children-children need to stick to children-children oriented games. That's what they're made for.
I try to find players closer to my age [I am 19] to talk to. Adults talk about adult things. No, I don't mean obscene things, I simply mean things that a child has little to no experience with. Jobs, work, cars, raising children, etc. A little puppy-love elementary or middle school boyfriend/girlfriend break up seems extremely.... uhh whats the word? "childish" compared to those kinds of things. Thats not to say I don't have my moments where I act like a total goofball but I think child drama, young teenage drama, and adult drama needs some thick lines drawn between them because those divisions do exist. A moving away best friend at school [child], a "breakup" [like, a non-serious "relationship" between younger teenagers] and a divorce [adult] are all very serious issues to the person experiencing them but I think we can all agree that the most serious and more easily sympathized with by a fellow adult is going to be the divorce and that makes the former two "problems" from the child and younger teenager seem extremely trivial despite all three of them being difficult to deal with.
This is not to say that I have anything directly against any younger players.I will and do treat them with respect with the expectation of receiving the same but I will stand my ground on my opinions.