I was at Google in 2011 and I remember the internal flame wars you triggered about performance reviews. You mis-characterized the process internally then, and you mischaracterize it now.
Perhaps you were on a dysfunctional team, or had a particularly bad manager, but this is most certainly not the general case.
Stack ranking was not mandatory, but the perf UI certainly let you stack rank your peers if you wanted. I never did and management never cared. There was certainly no curve, and managers did not have to create low performers by quota.
If there's one complaint I had about the Google perf system was that it rewarded popularity and networking perhaps more than competence and effectiveness.