>The general success ingredient is putting a small team of veterans on making the new system. Success always comes from a small team of engineers who are both domain experts and technical experts rolled into one. (Controversially, I think that generalises; all success comes from this, even for mundane keep-the-lights-on problems. And everyone else is just slowing them down.)

Fully agree with this for all scopes of projects. Larger projects are compositions of this principle with functional communications between focus areas.

There's no financial incentives for Maintenance though, which means "leaders" have less and less incentive to fix what they have versus building from scratch. In my experience in these cases it comes down to (like most things) whomever the least flexible person in a power position decides to do.

Fundamentally the problem with all large organizations is that desires and incentives become diffuse the more people are a part of it and the "alignment" of what should happen drifts, until eventually nobody cares to maintain the original purpose.

You can argue this is good or bad or inevitable, but either way it's a structural issue between the broader world changing, and a organization that seeks consistency