This reminds us that systems should be designed to function at the smallest scale that is practical and energy efficient (rather than the biggest). In some ways this is a value judgement. Permaculture usually favours small scale and local, over big scale and global.
This links to concepts like 'human scale', as Kirkpatrick Sale calls it, and the ideas of Ernst Friedrich Schumacher in 'Small is Beautiful'.
Small scale solutions and activities are more likely to be adaptive to local needs, respectful of nature and able to see the consequences of actions. Slow food, slow cities, slow down! Incremental changes can be more easily understood and monitored.
This concept links to one of the "Golden Rules" from Bill Mollison's Designers Manual - start small, get it under control and then slowly expand the perimeter - or put another way, don't take on too much too quickly, as you are likely to be overwhelmed.