What can you remove from a minimum diameter rocket and still have a rocket? You need something to attach the fins to, some how to hold the nose cone, and somewhere to put the recovery gear. We’re talking model rockets here, to start bringing in definitions from other areas would not make any sense, and worse, they’d lose the contextual meaning that we as a hobby rely on exactly in these kinds of discussions, which you acknowledge.
Can you give an example of what you mean by a minimum diameter rocket not being ‘minimum’? I’m not sure I’m following your logic here.
Tony