I can't speak to what the platform of the DSA actually is, but (1) they didn't cite AOC at all (unless I'm already mis-remembering it); and (2) some of the "alarming" calls for those positions deemed ultra-liberal probably aren't "ultra" after digging in more.
To know what AOC believes, you have to read what she's actually said. I may have missed it, but I don't know that she's waging war on capitalism. I don't think she's even calling for socialized medicine (which is different than single payer). Her calls for abolishing "for profit" prisons (regardless of her position's merit) isn't calling for abolishment of incarceration. Her call for the abolishment of ICE isn't, to my knowledge, calling for an end to immigration enforcement, but instead for keeping it structured along the way INS formerly was and out of the hands of terrorism hunters who are prone to civil rights abuses*. Etc. Etc.
That's not to vouch for her at all or to suggest she's a thought leader among the Democrats.
I think it was Tom Perez who purportedly said something about AOC being the future of the party, but that wasn't really exactly what he said. It was more along the lines that she is typical of a new voice in the party and that that new voice will be an important one going forward. I don't believe he was suggesting that SHE is the answer, but rather that a new generation has a different viewpoint and perspective and will make itself heard.
Hinging all that on AOC would be a mistake.
To her credit, though, and as I said someplace else over the past couple days, the advantage she (and likely others) is bringing now is a mindset unencumbered by experience and understanding of bureaucratic norms. That's good and bad, obviously. Structural norms have value. But, without intending to compare AOC to a child, sometimes breaking those bureaucratic norms allows for The Emperor Has No Clothes moments.
Finally, even if AOC is very liberal, she's not the king. At worst (for conservatives), she and others like her might push the conversation and negotiation a bit. That's my point about anchoring. Many Democrats believe the negotiation has skewed far too right for too long (e.g., Grover Norquist, NRA, climate, etc.)
*It would be useful if we tethered our immigration and southern border conversations to the reality of the numbers of the past so many years and use those numbers to quantify and explain any issue and the proper response given our current situation (as opposed to the false narrative that is not supported by data).