In my opinion, there is absolutely no way a junior / SWE1 could greenfield an app by doing anything other than following a youtube tutorial or similar step by step guide, and would have basically no understanding of the decisions made throughout. They would have no real experience with style, linting, no good opinion on libraries, no knowledge of accessibility, security, usability, nothing. They would end up with a basic 'hello world' application that would likely fall apart before you could even get your business logic in there.
If you have a SWE1 that can literally just greenfield an entire application and do it at a very high level, then they are a unicorn / 10X developer operating at a ~SDE4 level already.
I personally do not think the average SDE1 can meaningfully contribute to a quickly moving and efficient team. By the time they are even able to contribute regularly, they are SWE2/mid in my book.
I do have much less experience in giant beaurocratic slow moving organizations so I don't have an opinion on how all of that rigmarole works, I'm speaking more to highly focused small teams delivering at a high level quickly.
Sure, someone that is an entry level programmer will not have deep technical knowledge, that's not what I was trying to say though. My point is that levels only make sense in organizations that are big enough that tech leadership can't directly assess and compare ICs work because there's too much going on for any one technical expert to assess. Smaller organizations sometimes cargo cult leveling systems because it helps their ICs resumes and give a sense of progression even though the organizational problems that are the raison d'etre for staff+ levels don't exist at that scale.
To say it a different way: consider hobbyist developers who have spent a lot of time developing technical skills. These folks will tend to be very good at creating greenfield apps, and depending what they do, they may also have technical chops that are applicable to large companies as well. So they may be able to be hired as L4 or L5 (Google leveling) just based on technical chops. L6+ will be tough though, unless they have very deep specialist knowledge, because the most common L6+ work is about using technical knowledge to achieve outcomes that depend on navigating multiple teams and stakeholders in a way that the solo dev never has to deal with.
If you have a SWE1 that can literally just greenfield an entire application and do it at a very high level, then they are a unicorn / 10X developer operating at a ~SDE4 level already.
I personally do not think the average SDE1 can meaningfully contribute to a quickly moving and efficient team. By the time they are even able to contribute regularly, they are SWE2/mid in my book.
I do have much less experience in giant beaurocratic slow moving organizations so I don't have an opinion on how all of that rigmarole works, I'm speaking more to highly focused small teams delivering at a high level quickly.