This dynamic also occasionally occurs with Airbnb hosts, the scale quietly flipping from feedback to magnanimous compliance, albeit the added complexity of reviews sitting in mutual double-blind escrow. No such pact exists in the same manner for our hobby.
The minute the provider petitions for a 5, the scale collapses into a loyalty oath in which the majority of consumers are complicit. If a 4 or blanking (refraining from entering a 4 in spite of overall satisfaction) needs defending, 5 has already lost its meaning.