@josemanuel @mangeurdenuage humans have a lot of ways to provide value to other humans, and when someone is in need it's usually a particular need, and even if I don't receive something back directly I can expect that value will get back to my community somehow.
in the case of this vampire plant, you can tell a story about how plants helping other plants of the same species is some good genes to have in general, and you could tell another story about how humans might value albino plants and human intervention could lead to such a species breeding more than would otherwise be possible ... but in simple direct language, it's a parasite. It receives sustenance, it provides nothing. You should just call it what it is and not get distressed about the word itself.