This is true. I'm just responding to OP though, they said:
> Yeah its pretty scary, 6 years mean you've either only understood on one or two big systems, or you've job hopped more projects and never understood them in depth.
Which is blatantly false. I only need to provide one counterexample, and John carmack blows this assumption out of the water. I wouldn't expect the average developer to be anywhere near that level.
But if the top percentile is shipping over 20 commercial products and literally changing the industry with a technical innovation in only 5 years, then I would wager it's very attainable for an average dev to reach a "senior" level of experience in 5 years.
language is more fuzzy than binary logic systems, John Carmack is an exception rather than a counterexample.
And that's the point, comparing exceptional people to the general population isn't valid or relevant here.
Also, these people are typically on teams as juniors who are learning.
Consider that you immediately reached for someone who is over 50 as an example of a developer having a large impact in the first 5 years of their career. That really does say everything.
> language is more fuzzy than binary logic systems, John Carmack is an exception rather than a counterexample.
An exception is a counterexample. For example, are all prime numbers odd? No.
Why not? Because 2 is prime and even. This is exceptional because 2 is only 1 out of a (theoretically) infinite number of prime numbers that are even. This doesn't mean I can now say, "All prime numbers are odd".
The OP gave a tautology that basically went, "If you've only had 6 years of experience, then you only worked on 1 or 2 big projects OR you've job hopped and have a low level of understanding". John Carmack is exceptional, but also a counterexample to this statement in both regards. He was also the lead programmer at ID when he made Doom, not a junior.
Besides this point, what does him being over 50 have to do with this? He was 19 when he started working professionally if I remember correctly, which means he was 24 by the time he made several significant industry impacts.
Besides that point, here are some more counterexamples to the original claim. Mark Zuckerberg was 19 when he started Facebook. Alan Turing was 29 when he cracked the enigma. Djikstra invented Djikstra's algorithm when he was 26. Bill Gates founded Microsoft when he was 20 and released Windows when he was 30. I have plenty of personal examples as well, but it wouldn't do any good to mention them since they're not famous programmers.
Since you're insisting on putting it into mathematical terms, here it is.
you're insisting on 2-valued logic, language does not work that way.
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Here's what you're doing.
"seat belts save lives, therefore you should wear them".
"aha! There was this ONE car wreck where they would have died if they were wearing their seatbelt. It's a counter-example and therefore invalidates your point!."
Said no reasonable person, ever. What it IS is an exception to the general rule. Because it turns out, reality isn't 2-valued.
"Seat belts always save lives" vs "seatbelts save lives". The first is false according to your counterexample, and the second is true as long as seat belts save some lives.
Reality is not 2-valued. I don't understand why you're still arguing this point. Yes John Carmack was exceptional. And yes it's true that 6 years of experience does not automatically imply a junior level of experience. That's all I'm saying here.
> Yeah its pretty scary, 6 years mean you've either only understood on one or two big systems, or you've job hopped more projects and never understood them in depth.
Which is blatantly false. I only need to provide one counterexample, and John carmack blows this assumption out of the water. I wouldn't expect the average developer to be anywhere near that level.
But if the top percentile is shipping over 20 commercial products and literally changing the industry with a technical innovation in only 5 years, then I would wager it's very attainable for an average dev to reach a "senior" level of experience in 5 years.