Secondly, the issue isn't that google added DRM to chrome, it's that the DRM was pushed into an ostensibly open standard, but the implementation of that open standard is locked behind a licensing agreement with Google because it's illegal to make a compatible client under the DMCA, since that would be considered copyright circumvention.

If instead google and HBO had made a specialized browser app to handle the DRM or even just a browser extension that enabled the browser to understand a nonstandard html tag, then the argument that Google is using Chrome's footprint to to modify open standards to make it harder for people to compete with them starts to fall flat on its face (cw. no one is complaining that an HBO app for android and iOS is a monopoly that needs to be broken up). But doing it that way makes it much harder for HBO to acquire customers, because it requires customers to install a new app on their PC or an extension in their browser.