I mean IANAL but in a rational world there would be a minimum of grievance requirement before being able to file such a lawsuit.

There is, that's what the discovery phase of the lawsuit is for. That's what the dismissal phase of the lawsuit is for. The issue isn't that these things don't exist, it's that these things are the most expensive parts of trial.

Imagine the reverse case where you find out someone has started a campaign to keep you from getting hired anywhere. You know they are doing this because someone tips you off on this happening.

You do not have enough evidence to prove that this is happening in court at the moment of the lawsuit but you are damn sure that the person you are suing has a trail of documents proving your allegation and if they don't the third parties that didn't hire you likely do.

If you find enough evidence you can get the person to settle before trial. If you don't find any evidence you can either go to trial and lose or simply drop the lawsuit.

The unfortunate thing is gathering minimal evidence, which really is the job of lawyers beyond just knowing the law, is a time consuming task for someone (Usually multiple someones) that is pretty expensive.

Now, to the actual real problem. It's actually 2 fold.

1. Gigantic lawfirms gobble up basically all lawyers that have any sort of talent. This drys up the pool of lawyers available to represent people and consequently drives up prices, for everyone. These lawfirms can keep increasing their prices because their rich clients will pay for it and the smaller lawfirms that would represent your case can similarly raise prices because there is no competition.

2. These gigantic lawfirms and big companies when they sue take a TON of time and resources from the court. You can expect 100 or 1000 issues being filed by one of these lawsuits just at the very beginning. They apply a "Well, there's a 90% chance you'll win without these motions, but there's a 95% chance you'll win with them. So we'll file whatever we can to make sure every single avenue is explored. Oh, and we bill you for the hours we spent with our law ghouls scouring legal books in the dungeon."

These 2 issues mean the courts are constantly flooded, any lawsuit (especially against someone with the resources) takes a long time to resolve, the cost will be astronomical on both sides because the legal team on the other side needs to respond to every court filing, and finally the number of available lawyers will go up because there is little competition forcing them to have lower prices.

The reform we need, if anything, is some sort of penalization on these giant firms for wasting time. Perhaps applying sanctions to the other side if it's found that they spent 90% of their filings for stuff they never used.