I know other people have already refuted this, but seeing the original message still going around I’d like to point out just a couple of reasons why this request - while well intentioned - misses a lot of key points:
1. This is working under the assumption that tumblr is a space solely (or at least primarily) for teenagers/kids and that simply isn’t the case. Historically the creation of fanfiction, fanvids, fanart, etc. has been done by people in their twenties and older. Think about how many years it takes to learn how to craft a good story. Think about what you need to pull something like a con together. That person with the Skill you admire? There’s a very good chance they’re an adult. It used to be that kids pretended to be 18+ because they knew online fan communities were adult spaces. I’m not sure when this switch happened, but it needs to stop.
2. It is not “a little weird” that people don’t put their age on their blog. I have mine because I’m comfortable sharing it and my fan identity/irl identity are already really conflated, but a lot of people - most people - want to keep personal information to themselves. There’s nothing wrong with that and insisting that we reveal that information is all kinds of wrong. Can you ask someone their age? Certainly! Maybe they’ll tell you, maybe they won’t, but regardless you are not entitled to that information.
3. The children on here? They are not my responsibility. If kids/teens are worried about who they’re talking to then they should either a) be careful about who they interact with or b) not use this website. If they’re too young to understand this then they’re too young to be online without parental supervision. Now, how can a teen be careful about who they interact with? Check the person’s blog. See the kind of content they post. See if there are any hints about their age (mentions of school, job, birthdays, etc.) - or again, just ask! I’ve had plenty of people on here decide they only want certain types of interaction with me after discovering my age and that’s fine. But it’s not my job to monitor everyone else’s internet use.
4. Finally, I find the language here to be rather concerning. “A little weird,” teenagers are “lured,” leading to things that are “much more insidious”… all of this, whether intentionally or not, frames anyone 20+ as intrinsically predatory. It also takes agency away from anyone under 18. Teenagers aren’t “lured” into talking to me, they make that decision on their own. They are their own person capable of making their own decisions, gathering information before making that decision (like asking someone’s age) or, if they can’t do these two steps then again, they should not be online. We’ve come right back to point #1: this is not your space. It’s our space. I’m not some trespasser here who only gets to stay provided that I cater to those younger than me. If anything, based on how much of online content is geared towards adults, kids should be working under the assumption that they are speaking to an adult until proven otherwise, especially on websites like tumblr that cater to all ages. Don’t assume you’re talking to another teenager. Don’t project onto a person and then get mad when you find out you’re wrong. That’s not them tricking you, that’s you failing to take responsibility for yourself.
You want to know someone’s age? Ask, and then work with the answer you’re given. But someone failing to give you private information up front isn’t weird or predatory or insidious. The quicker everyone realizes that the better off we’ll all be.