If she'd said something like, young people are all irresponsible, then I might agree. All she said was that Alienbetta was too young. When you're younger, you don't always have the money or the freedom to do everything you want. You're often at the mercy of your parents and their wallet. (Been there, done that). You think your fish needs a heater and all that other good stuff but you may not be able to provide that at 12 and your parents may not be willing.
It doesn't mean that young people can't care for fish but that it makes it a greater challenge and if there's a problem, they're not always able to address it. There's nothing wrong with that. That's just the way it is, again, in some cases. Sometimes you just have to wait until you're better equipped to care for an animal. It sucks, but there it is. We've ALL been there. :)