>surely having a washing machine is a bigger change to your life than having a chainsaw

The relative effect of these devices varies by location. This assessment might be true in Southern CA, but if you're heating your domicile using wood in Northern Ontario that chainsaw is looking pretty good!

a washing machine, with little parts that can be replaced with wood or metal, seems like the kind of thing that can be kept in good working order for a long time.

I'd be leery of a chainsaw with handmade parts.

I also kind of wonder about lubricants and fuel in a chainsaw, how hard is it to safely duplicate those oils?

In the movie The Devil's Playground there is a discussion about how the Amish adopt technology. If I remember correctly, the criteria was based on whether the technology was disruptive to the community (i.e. how it affects the relations between people rather than an individual's day-to-day life). It's been more than ten years since I've seen the movie and I'm going on memory, but that made a big impression on me.