[kilburn]

Fist, the 10,000 hour rule is false common knowledge [1,2].

Second, splitting a general role ("backend engineering") in arbitrary atomic skills doesn't make sense because there's no end to it. Backend engineering -> OS fundamentals -> Driver programming -> Hardware design -> Boolean logic -> Set theory -> and so on...

Third, all engineering roles have cross-cutting concerns. You do need some network knowledge to be a "backend guy"... but also to be a sysadmin, devops, etc.. It's not like all these roles exist in a vacuum and you're starting from 0 if you switch between them.

Finally, most people that think of themselves as experts in some role, language or framework end up in the "1 year of experience repeated 10 times" trap. True experts are also somewhat generalists too, because you can't built a tall knowledge without growing the base too (pun intended).

[1] https://www.bbc.com/future/article/20121114-gladwells-10000-...

[2] https://nesslabs.com/10000-hour-rule

[dijit]

10,000 hours, whether true or not, is a ballpark and even if it's patently untrue: it will always require some non-trivial amount of time to get good or master a particular subject.

Not all subjects are equal, granted.

having overlap in knowledge between roles is also somewhat granted; being a complete master in backend gives a person a lot of knowledge towards being a sysadmin (maybe even 60-70% of the way to being a master in that direction!);

But, you've failed to convince me that any single human on earth can do "everything"; even if a person could literally master all technologies in use (not counting your strawman of driver programming) then there would still be a discipline mismatch.