Don't give up just yet.
There are plenty of refinements still to be made to Steemit. Nearly everyone wants the system to be fairer, even people who post bullshit just because "if you can't beat em, join em" ..
Yes, it's unsustainable, but this is beta. We will get there. It took Google years to make spam a pointless endeavour.
In just some short months Steemit has been created and tweaked to a reasonable starting point. We've a bit of work to do. Not just the devs, but as we conduct ourselves as a community. Ultimately though, the spammers will lose.