I have to imagine Google added these headers to make it easier for them to identify agentic requests vs human requests. What angers me is that this is yet another signal that can be used to uniquely fingerprint users.
You could already do that with the user agent string. What this does is distinguishes between chrome and something else pretending to be chrome. Like say a firefox user who is spoofing a chrome user agent on a site that blocks, or reduces functionality for the firefox user agent.
Like people spoofing the Chrome UA in Firefox to avoid artificial performance degradation inflicted by Google on their websites...
If they only look at this header, then legitimate users using non-chrome browsers will get treated as bots.
If the these headers are only used for chrome user agents, then it would be easy to bypass by using headless chromium with a user agent that spoofs firefox or safari.
Indeed, even for those who require a round of mental gymnastics before they concede that monopolies are, like, "bad" or whatever, GP points out precisely how this would constitute "consumer harm".