I think the question is actually a little more complex than meets the eye. There are different facets to being a "newbie" that interrelate but may not all be considered when a person is evaluating oneself or another
First there is the skill factor. Has a person become significantly adequate in the water to be a confident, self-reliant diver? Consider the “you don’t know what you don’t know” factor when you evaluate yourself. Look for feedback from trusted, more experienced divers you associate with.
That being said, one can be a quick learner and have excellent skills yet still be a “newbie”. It’s just the simple concept of having some real life experience. One must get out and dive and work through the real life issues that come with diving. This will be the only way one can gain experience and grow in a “responsible confidence.” And, as others with more experience than me have said, this can be compartmentalized into different types of diving experiences, so the learning curve can start over again in new diving environments.
I think there is another factor that some may not necessarily relate to being a “newbie”. And that’s a level of wisdom and maturity. One can have awesome skills and even a fair degree of experience but still not be a wise diver. You know the type. Those that think they are invincible, or those that never listen because they have it “all figured out”. Again, this one may not necessarily be related to being a “newbie”. I’m sure there are people out there that never outgrow this attitude as well as “newbie’s” that never display this approach.
But as I consider my own, fairly new, journey into diving, as I consider the possibility of my loved ones getting into diving, or if I ever was to become an instructor, I would want to see growth in all of these areas.
Does the diver have the skills to be safe and self-reliant?
Has the diver put in the bubble time to have a set of rounded experiences?
Does the diver display the maturity of a quiet confidence in their diving that is balanced with being a responsible, always learning member of the diving community?
If the above questions are answered yes by both the diver and his/her diving peers, then, in my mind, they are no longer a “newbie”.
As people like Walter, TSandM, Scubadad1 said, there is always something new you discover, new things to learn. When you start thinking that you know everything (not just in the diving) that's the moment when you might get in a trouble.
