I'd love to hear why you think that is. It feels to me that the web benefits and has benefitted a ton from Google's investment in Chrome and newer standards. Chrome itself doesn't make any money and so I fear to me that splitting it out would leave it scrambling for a revenue source and that there would be far less investment in it then there currently is.
It feels like keeping the threat of antitrust action on Chrome is a more effective way of keeping them in line. I don't see much abuse from their dominant position (in the browser space, search is another question) so far, but making it clear that regulators are watching them closely is IMO the best way to ensure interests align.