Anecdote - Part 1:
Years ago I was hired by Racal as a contractor to work with a team on a CAD package they had going. On the first day the project manager dumped a half meter high stack of paper on my desk. It was all the out sanding bug reports they had been collecting for a year or two. I was set the task of investigating all those bug reports, finding the ones that were reproducible, and fixing them.
Great, I knew nothing of the gigantic code base and only a slight clue what it actually did. I set to work. For the best part of a year if I was fixing bugs with one line changes at the rate of one per day that was a good week.
After that, they put out a major upgrade, and they thought I had done very well so I was allowed to write actual code for new features for the next cycle. Even lead a small team on a subsystem.
Anecdote - Part 2:
On that team was a very bright young software developer. He was amazing. I have never seen anyone write so much code so quickly, not only that this was pretty hairy design optimization algorithms, not only that his code generally just worked. Just brilliant.
Until, one day he did not turn up to work, which was odd. Later in the day he called me, he could not tell me where he was or what he was doing or why, he was making no sense at all. Turns out he had some kind of nervous break down and was off work for weeks. On his return he was a different person, very slow, unreliable. Eventually the company fired him. A very sad case.
What does it all mean?
No idea. But I'm pretty sure that if anyone doubts the statistic they have not looked very hard at what goes on and never made the measurement themselves. They only remember the days when they churned out a thousand lines of code. Or they have hired some code monkeys that endlessly churn out code cut an pasted from stack overflow or recycled from other similar projects.
Memory in C++ is a leaky abstraction .