[themoonbus]

Because Google is the decider of what constitutes "slow"? You have a single organization deciding what the threshold is between slow and fast. And, they also have a Google-approved solution (amp) that I'm sure they will tie into the recommended actions for "slow" pages.

I'm not saying it's a walled garden (that's a more extreme situation on the continuum between open and closed), I was just using the phrase to illustrate my point that the end-user experience isn't the only factor to consider.