[acjacobson]

Some of them are, some not as much. There are certainly more obvious poetic devices like a "murder of crows" yet there are still many other collective nouns that are more "legitimately" part of English - pack, herd, pod, flock, swarm, and school for example. You don't have to know these terms as using 'group' would be understood - but they are common enough in books / documentaries.

[umanwizard]

You’re right. I was referring to the more obviously made-up and never used ones.