> which is still potentially troubling but very different
You always have to judge a developer's gaps/knowledge given their context. We're dealing in technologies that have sub-sub-sub-sub-disciplines that a person may have expertise in which result in them missing huge portions of the languages' features. I've learned that this hyper-specialized developer can be as effective as anyone -- the ability to rapidly acquire, integrate and use new knowledge with whatever tooling is required is far more important to me than whether or not a developer has large gaps in the tools we use[1].
I'm nit-picking a little, but it's a habit of mine to turn around discussions at my office that go something like "How can any web developer not know (x)?"[2] Ask a developer on a conference call if they're familiar with some obscure technology, and you'll hear ranges of qualified "Yes" responses and a whole bunch of clacking while each Google's various bits of information. How much easier is it if everyone just says "No, I don't" and asks the person who brought it up to explain. It's really hard to get developers past "Imposter Syndrom" and open to admitting their gaps so they can be accounted for in planning. Even where I'm at, now, I see it from time to time and this is at a shop with excellent culture and a focus on projects/products that are new inventions/creations.
And, unfortunately, it causes me to judge that individual unfairly, myself -- I've been writing code since I was 13 years old. I have written a lot of code. My goal is that the best code I wrote 6 months ago should at least slightly embarrass me, today.[3] And I guarantee, over the years, I've written code that is worthy of posting on a site like this. I can't imagine what kind of insanity my first "useful" rust program will end up looking like, but given the memory-safety rules imposed, I'm expecting to have to integrate a new mental model that will result in some comical implementations.
For me -- this work has a way of either humbling you or down-right beating you up with how often you're reminded about what you don't know. I think it gets worse as you learn more almost feeding the whole "ageism" in the industry -- middle-aged developers are far more honest about what they don't know and some are just beaten to death by the treadmill. I have watched, over the years, as developer after developer has left for "management" or leaving a shop like the one I'm at for a global multi-national to work on the most boring internal enterprise-y waste -- consistent/easy, but pointless. For the few that I was close enough to that I got more than just "PR answers", the crux of it was burn out from never feeling like you're actually "knowing" less about what you're working on[4]
[0] Outside of `enum`s in my language of choice, which perform best when flags are checked/appended using operators. But even that is an unnecessary optimization nearly always, there's a ".HasFlag()" method that I simply forget about because it was taught to me in my teens, it's implemented consistently in a lot of languages and it's muscle memory at times.
[1] I've recommended the hire of individuals who, outside of "they have been writing C# code for a decade", they hadn't touched the part of the framework the job was for -- i.e. they were Desktop devs applying to Web, Web applying to mobile, and many candidates lack even basic Docker/shell knowledge, etc. All ended up picking up what they were missing on-the-job just like the rest of us.
[2] Because, unlike every other field, when "(x)" became "old", it had been on its 5th version, 4th major API change and was born about three and a half minutes ago.
[3] Sometimes I'm unfair -- the reason I'm embarrassed is because I didn't use a very obvious feature, but at the time I'm looking at the code I'm also forgetting that said feature didn't exist back then. But often it's just because I've continued to read/study/do.
[4] These were not developers who were suffering from mental decline with age and were among the better I've worked with. I really think it's a case of "learning about something new" simultaneously adding to "discovering that your skillset does not include this massive body of knowledge around your small usage of 'something new'". You learn way more about how much you don't know than you add to your total knowledge making you feel 'net dumber'.