The more of an asset class is owned by passive investors (now approaching 50% for US equities), the greater the reward for the type of behavior you point out. It's effectively leverage: any "bug" found gets multiplied across the portion of passive investment affected.
Well, passive credit is far worse than passive equity. At least in equity, you are buying more of the largest companies, in credit, you are buying more of the larger issuers of debt...
