If a system is impossible to maintain, that system is nothing of value, and therefore doesn't fit to any sensible definition of 10x.
I have always assumed that the 10x means value creation, not some kind of "lines of code" output or other nonsense. And for sure there are 10x programmers, maybe even 100x. I have been mostly working at startups and you see these early stage decisions and designs that create huge costs when the company starts to scale, similarly you have some decisions that might save huge amount of costs during the company life time, or allow better revenue generation etc.
I have always assumed that the 10x means value creation, not some kind of "lines of code" output or other nonsense. And for sure there are 10x programmers, maybe even 100x. I have been mostly working at startups and you see these early stage decisions and designs that create huge costs when the company starts to scale, similarly you have some decisions that might save huge amount of costs during the company life time, or allow better revenue generation etc.