Who us?

Your Google account is referenced by Inter Process Communication (IPC). A voluntary decision by the user when logged into Play Services.
Running Play Services in a secondary user means you can End Session, put it back to rest and prevent any further running. Play Services and Google API can only run if you use the former or install apps built with Google SDK that include them. You're in total control. Happy to discuss it more if you have concerns, questions etc.
MicroG is there in the system doing it's thing regardless all the time along with Google connectivity checks, network time, attestation key provisioning, SUPL, PSDS (Pixel 6 and 7), eSIM activation. Nevermind that while the 'implementation' is open source the rest is still privileged Google Services on other OS.
Whatever though, we all pays our money and makes our choices, your prerogative to use what fits so long as you're happy alls well with the world.
Take care and be well.