25%-50% of the market? Where do you find them? I've never seen a programmer unable to write at least a fizzbuzz.
+1 however I think there is a 3rd kind of developer as well. The 3rd being those who CAN do fizzbuzz/codekata style tests but when faced with a real programming problem in real code base they falter.
There are a thousand gradients of skill level, dividing it into 2 or 3 stereotypes is facile and pointless.
There are actually just millions or billions of discrete points, one for each programmer. Implying that they can be approximated by some kind of continuous gradient is quite frankly insane and unfounded.
The gradient covers all the hypothetical programmers that could exist but happen not to.
That's called a model.
Each of those 'programmers' is millions or billions of data points, one for each neural circuit. Implying that they can be approximated by a single discrete point is disingenuous and misleading.
1. Those who are good developers 2. Those who can't write any real code (cargo cult or cut&paste developers, e.g. the 25% who I didn't hire over the years because they were not able to FizzBuzz)(25%-50% of the market)
The 10x comes from comparing (1) and (2) - although dividing anything by 0 is larger than 10x.