Imagine that I accidentally hammer my thumb and sue my hammer for the injury. I find it guilty and have it destroyed. How did my situation improve? All that happened is that I'm down a hammer.
Your hammer is literally just an extension of you so you are just suing yourself. A company is not just an extension of its shareholders. In fact, the whole point of the corporate form is that the business is separate from its shareholders legally, financially, and for all purposes (except for some reason First Amendment rights).
Specifically, the harm they're seeking redress from is a drop in the value of their stock.
And the redress they are seeking is also a drop in the value of their stock.
This is the conceptual problem. Shareholders have not suffered any harm that can conceivably be redressed by a shareholder lawsuit. The only possible effect of the lawsuit is to hurt the shareholders even more than they were hurt before.
They can be filed by shareholders who were harmed by prior corporate account. Not sure for this concept is so hard for people to understand.
TLDR we're taking about different groups of shareholders.
The idea is that, in your capacity as owner of the company, you sue the company for screwing you over, and it pays a fine to you. But that makes you worse off, because it makes the company worse off, and you own the company.
In the best case scenario, where the suit is costless and 100% of the fine goes to shareholders, the shareholders come out of the suit no worse off -- and no better off -- than they were before they sued.
In any other scenario, they come out worse off.
Imagine that I accidentally hammer my thumb and sue my hammer for the injury. I find it guilty and have it destroyed. How did my situation improve? All that happened is that I'm down a hammer.