One thing I've heard engineers say is: "Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands."

The point is that to make something truly economical that will last takes a lot of experience. And what counts as "barely stands" to an engineer is not the same as what it means to you.

Yes if you just slap up a deck it'll be ok for a few years. But I wouldn't get carried away trying to lighten designs and skimp out on footings without a good working understanding of what time, water, and gravity will do to the ground and materials you are using for the deck.

Or if you are ok with things starting to get shitty in a couple years... Go for it I guess.