There are people who think that monopolies are the singular goal of system creation. This factor rejects that. There are those who think that big systems should be broken down into tiny parts to the nth degree. This factor also doesn’t fully accept that.
This factor is about building resilience into the system, rather than breaking things apart, and not necessarily splitting systems into tiny parts, but making complex systems deployable in small units.
The systems-thinking here is inspired by rebel cells (see the Bajoran resistance). Small autonomous units: take one out and the rest continues. Each unit is capable of a wide range of abilities, not just a thin-slice (e.g. this isn't the unix philosophy, although that feeds in).
"Many small things" is also inspired by healthy biological systems, as opposed to the proliferation of hypergrowth cells that eventually poison the host and suck the life out of the system. In biology, we call that cancer.
Many small things are more securable. Attack targets become more distributed. The economics of breaking into any cell—or instance—become lower return on effort.
Small systems are also much easier to understand, to distribute, and to run locally.
Small systems are easier to modify, to customise, and ultimately, to own.
The result: every user of software systems built this way is in control: control of where their compute and storage is hosted, control of whether they receive automatic updates, control of whether they update at all.