Maintenance vs. Innovation
Tech culture fetishizes "innovation" (the new shiny thing) and neglects "maintenance" (the hard work of keeping things running). Stewardship re-centers maintenance as a heroic act. In the Long Now, the Steward is more valuable than the Disruptor.
The Fiduciary of Code
A Steward acts as a fiduciary for the code and the community. They ensure that Legacy Systems are not just discarded, but understood, preserved, or gracefully composted. They protect the "Commons" from "Enclosure."