I don't think it's fair to say the break-up was a failure even if in the near term they still coordinated. In the long term, the oil companies competed with each other. Even if Rockefeller became wealthier, it only adds to the original point: breaking up monopolies unlock value for shareholders and increases efficiency. I highly doubt anyone in the main stream schools of economics would call the Standard Oil breakup a failure. That Rockefeller wasn't punished is immaterial to the breakup itself. The point here isn't to punish Bezos or anyone else. It's about efficiency and fairness. In that sense, that goal was accomplished. No single oil company today wields the power that SO once did.

Also, those guys meeting up together at Rockefeller's house to coordinate would likely be illegal today and probably was back then too.

or Costco? $130B in revenue and I dont hear clamor for Costco to be split from Kirkland.

By this logic Apple shouldnt be allowed to have Apps in its App store, right? Or are they banned from selling first and third party phone cases in store?

CVS shouldnt be allowed its own generic drugs.

At what point does this become "companies arent allowed to make/sell their own products if they also resell other companies products."

And lets be serious: you want to take away Google's ability to choose the ranking of results? Thats their entire company's purpose. People go to google because they like the order the results come in. If google starts delivering bad results, that opens opportunity for other companies.

Since multiple people are asking this: it would apply to Walmart and Costco under her proposal because they both have $25B in revenues.

This is just the first step in a new conversation about confronting monopoly in America. There hasn't been a bill written yet.

Walmart isn't a platform (excluding Jet.com). They purchase goods (take on risk) prior to selling them.

Amazon is a marketplace meaning the seller takes on all of the risk and pays Amazon for the privilege. Amazon then uses the data that marketplace generates to undercut the sellers with their private labels.

From the Warren post:

Companies with an annual global revenue of $25 billion or more and that offer to the public an online marketplace, an exchange, or a platform for connecting third parties would be designated as "platform utilities." … These companies would be prohibited from owning both the platform utility and any participants on that platform.

Thus Safeway would be exempt from the regulation because (a) they do not offer an online marketplace and (b) they do not connect third parties (but instead act as an intermediary).

Similarly, it appears that only Amazon Marketplace, not the retail arm of Amazon, would be affected by this regulation.

As Elizabeth Warren makes clear in her post, "demonstrated consumer harm" isn't the only justification for antitrust action. We can't demonstrate the innovation that would occur in a competitive marketplace, but we break up monopolies with the faith that it will. This was the prevailing view until the late 20th century. Hopefully we'll get back to it.