10 years ago i wrote a php web chat in 2 hours or so. I pretty much never look at it but the tinestamps suggest it always worked.

I could add more features to it and those will also work.

A friend once worked on an application with a huge team. He often pointed out the window at a large costuction site with a comparable number of people working. He made countless jokes about real work, a real system, real organisation etc Then one day the building was finished and their application kept crashing in production.

It's part of a constantly evolving ecosystem. It's a stable product because reliability engineers make it so and software engineers get the integrations right.

> Cause it's developed

You can napkin-math this. How many different team-sized components do you think go into it? If the code were on GitHub, and all they had to do was just update dependencies below them in the stack, and bump the version number for components above them,how many Dependabot PRs would be opened per week for software that's "done"