I'm not quite sure I get what you stated here. When you promote an article on the promoted section of steemit you do use your funds. And those funds are destroyed via the null account, thereby taken out of supply. But forget this for a second because article promotion via steemit isnt a very big part of this blockchain.
Let's step and consider what's going on. Steem is just a stake weighted blockchain. Writing articles is just one way to earn in hopes that others use their influence (read influence derived from staked steem in the form of steem power). So when you write articles, you are hoping that others upvote you (use their influence and say you deserve more of the future inflation).
But steem is just a blockchain. As more dapps grow, more functionality outside of article writing is becoming available. For instance, take drug wars. By sharing a fight in the game on the chain, a robot upvotes your post. Take Steem Monsters, by playing games you get cards which have steem value on the internal market. Consider magic dice, where betting in a dice game one also gains tokens that offer dividends as you slowly become the house the more you play.
The point is steem is just a blockchain, and people tend to think it's only about post writing. It's not. It's a versatile stake-weighted blockchain that is growing and whose real world value is growing as more and more ways to bring in external funds continue to be onboarded.
RE: Screw the market. I'm buying more STEEM