Why you'd be an idiot to pick 1000 mediocre programmers over 5 great ones

The answer is actually much simpler than that:

Any mediocre programmer will write unmaintainable code in the long run. At some point one of three things will happen and always do, no exception:

1) They get too frustrated to work on this POS that they wrote and leave.

2) You give them tasks that eventually become impossible to be completed and fire them because they can't do anything you ask for in a reasonable timeframe.

3) They entrench and keep working, you ignore timelines and code complexity hiring more mediocre programmers to help the ones who need help. You just wind up paying money. End of the day your product works BUT the second any competitor with 1 good programmer pops up your entire business is screwed since with 20 developers you can't keep pace with a single dude having close to zero expenses making pure profit off of any money being made, while you wind up having to hire sales and more programmers, paying insane amounts while your competitor(s) slowly chip away at your business until you cant maintain enough clients to feed your ever growing maintenance needs.