The goal isn't really self-sufficiency. The three things I'm addressing are:

1. The complexity and expense of importing replacement and spare parts for locally-operated equipment. That includes farming equipment, but could be other things too. Right now, you have to order a long way to get things, typically to an urban area that you don't do enough business with to avoid being gouged. Which brings me to

2. Improving economies. If you have many villages with this kind of setup, all replacing farming equipment and repairing vehicle parts using a smaller menu of raw materials, you get higher-volume, more commoditized markets.

3. Time to repair / opportunity to innovate: You can't keep an inventory of spares when you're living hand to mouth. So you have to order a part when it is needed-- impairing local activities significantly while you wait for delivery.

I didn't think of the possibility for villages to barter and trade with one another, but it's definitely a major plus. Suddenly, the piece of steel you need you can get locally, get the spare part made, and repair your vehicle/agriculture equip/etc quickly.

Like I said, this isn't intended to be a panacea, or even a second or third tier solution. It's designed to make by small steps the transition towards real indigenous economies.