It's superficially true of any large stewardship organization. After N years some significant percent of projects will be on their way out. These will continue accumulating year over year and they potentially won't be disposed of for decades (and for good reason).

Meanwhile only a vanishingly small fraction of projects remains at the center of public attention for an extended period of time. People develop a skewed perspective because we interact with many of the most popular projects on a daily basis.

https://openoffice.apache.org/ is the context in which I've seen this saying get regurgitated the most.