I never got this line of thinking. I'm already disincentivized from spending because simple investments are likely to outpace inflation. That's a good reason to save as much as I can, but I still buy things, and it's not like I can put off buying food for a year so that prices drop. What's so different about this incentive to save and it being a part of the economy?
Yes, because most people spend most of their money. I'm saying deflation seems unlikely to change that, since a strong incentive to save money already exists, in the form of retirement fund.