GrapheneOS actually recommends against using Aurora and instead just using the Play Store, so this shouldn't really hurt users. For extra privacy, you can sign into the Play Store with a Google Account that isn't tied to anything else.
For instance, I use GrapheneOS because it provides better security and privacy out of the box than LineageOS, but I'm also not so paranoid that I'm going to just blindly listen to advice against using F-Droid. What I want out of my Android instance is good security defaults with no bloatware, not to stop the NSA from looking at my travel photos and what HN articles I once looked at. It's okay if my OS is great but not perfect.
So yes, I am a GrapheneOS user who is [modestly] hurt by this. Signing in with a dummy account is just another one of those things that will end up being futile in years to come when Google requires iris scans, DNA samples, and anal probes in order to get a new account. Personally, I'd prefer installing whatever software I want on whatever devices I [pretend like] I own, without telemetry or jumping through hoops.