I'll give a shareholder's perspective. Management, when left unchecked, frequently engages in in wasteful empire building and prestige projects. The most apparent manifestation of this is in mergers and acquisitions. Decades of evidence shows that the median merger destroys shareholder value for the acquiring company.
Imposing strong controls on corporate management is one of the most important thing that shareholders can do. This might take the form of independent boards, which aren't handpicked by the CEO. Or the removal of poison pills (which raises the threat of a hostile takeover for underperforming companies). But most important of all is the existence of transparent, consistent, regularly evaluated metrics. That means quarterly earnings targets.
Like any job, CEOs need consistent feedback to keep their incentive aligned with those who employ them (shareholders). Management has shown time and time again, that when monitoring is weakened, they go off the reservation and destroy shareholder value. The good thing about earnings is that it's they're easy-to-measure, hard-to-fake tangible proof of continuing performance. In contrast stories about "long-term value" or intangible promises of future rewards are usually BS used to justify extravagant empire building while the CEO uses the company's balance sheet as his personal piggy bank.
Lest anyone think that evil Wall Street shareholders are hobbling visionary CEOs, observe the rare cases when management does prove its credibility. Prime example is Amazon, which time and time again has scarified short-term earnings for long-term development. And nobody could possibly claim that it's punished by Wall Street for this. The difference is that unlike 99% of CEOs, Bezos has conclusively proven his ability and alignment with Amazon shareholders.