When agile is done correctly you are right. But agile, like socialism, is always "perfect world" scenario stuff.
To be fair Capitalism is also a "perfect world" scenario. You can paint it red (communism) or blue (capitalism), but what we have in reality is the very same modernized Feudalism.
No, capitalism is self correcting. Capitalism acknowledges flaws but allows for markets to fix them. Socialism does not, can not and will not do so. What you're talking about is crony capitalism which is a mix of capitalism and socialism where government picks winners and losers.