It doesn't ignore scarcity, scarce goods are inherently more labor intensive. And it doesn't presume intrinsic value, the labor necessary is a subjective concept so the value must be as well.
You're probably right about it's use in understanding a capitalist market, Marx spends no shortage of time on how capitalists warp that basic idea.
You're probably right about it's use in understanding a capitalist market, Marx spends no shortage of time on how capitalists warp that basic idea.