According to the 'Canadian Homebuilder's Association Builders' Manual' (2001), "These foundations have performed successfully for more than 30 years, but are not widely accepted in all areas of the country.

Pro: Highly insulatable.
Con: Requires careful engineering to resist backfill pressures.
Cut ends must be treated with the toxic stuff. Requires polyethylene membrane to protect exterior plywood sheathing.

As a reference point: in the far north where pile or pier foundations are used to bypass unstable layer of upper soil to bear direclty on permafrost, steel piles are quickly replacing wood. The backfill for these is basically a slush slurry, so maybe the high moisture content in this context makes a difference.

A local straw bale house constructed on pier foundation uses old telephone poles (treated with heaven knows) has been sitting pretty for on 15 years.

I have seen posts treated just at where they come into contact with topsoil. This would be the most biologically active level of the soil with insects, bacteria, run off, hungry hobbits, etc.