I am not familiar with this technical term.
I find this thread confusing, in that you seem to be arguing against a collective term for non-vertebrates, but you have started multiple topics contingent on this very distinction.
What would be the effect if every vertebrate suddenly died
Is anatomical degeneration impossible in vertebrates
I admit that these discussions are well above my expertise, and I do not think there is any shame in that – my education and work has been in other areas – but for that reason alone I think “invertebrate” is an important term. It is accessible to those of us who haven’t the same knowledge. We recognize the definition and can begin to sort information using this binary. Even if we are not always correct, it is one measure we can use.