That's a really reductive but actually completely accurate description.
The poem was supposedly aimed at children, but in practice is telling young girls to fuck their besties until they're ready to have kids and to be careful about doing drugs because you might find yourself selling your body to foreigners for a hit.
It's also about the virgin cure which, you know, have fun looking that one up, but more importantly is the author navigated the prudish morals of the time so well most people never actually realized what was happening.
It's just about not trusting the Fae Folk, officer, I swear π
So, yeah, a classic of Victorian literature and a little bit more than a "smutty poem"