It is if the distinction between prepubescent children and postpubescent children is relevant, which certainly is the case in our current system of laws.
Furthermore, failing to observe such distinctions makes every single term that describes any kind of activity that some people don't like--pedophile, rapist, etc.--all equivalent; they all just mean "bad person". But that makes it impossible to have a useful conversation at all, because "bad person" is not a useful category if you're trying to figure out what to do about such people. You have to look at the specifics. If you refuse to look at the specifics, then you're not helping to do anything about the problem; you're just virtue signaling. "I think all of these people are just bad!" Okay, got it, thanks for sharing.