Tackling the 2019 MW Exam Part 1: Are yield restrictions necessary to produce high-quality wine?

Fruit thinning, green harvest, restricted yield, whichever name it may go by there are few canards as distinctly pervasive as yield-restriction. Across Europe, the belief that yield restriction is directly correlated with amplified wine 'quality' is so widely held that one can almost predict the nature of questioning at any tasting, visit or seminar. Let's stop for a second; just how accurate is this belief? Is yield restriction really a fundamental requirement of high-quality wine production or is this hypothesis flawed?