I think that point 1. is caused by the fact, that the industry tends to divide programmers in two categories: most competent ones become architects and lead dev

I think that point 1. is caused by the fact, that the industry tends to divide programmers in two categories: most competent ones become architects and lead developers and are hired when you need to build new software system from scratch. After the system is built you let the people who created it go, because you can't afford their salaries and hire younger, less talented people to maintain it. So, instead of "software rots" i would say "software evolves to reflect the competency level of it's current maintainers"