I'm not an economist, but I think the Fed distinguishes between these activities: "saving" means holding money in accounts that are subject to the FDIC's reserve requirements, which in turn means that banks can't use (all of) that money for investments. "Investing" means circulating money in instruments that aren't generally subject to reserve or similar requirements, meaning that it's supplying liquidity to the larger market.
I agree with your broader point about consumption (we really need to correct our infinite-growth mindset), but an economy that encourages excessive savings is about as bad long-term as one that encourages people to shove all of their money into the market.