You can allege anything you want in court and proceed exactly like someone having a "legitimate feud." You might be punished later for making up a bunch of bogus claims, but you still got the information you shouldn't have.
This is especially effective if you're a powerful person or corporation and can find a litigant willing to sacrifice their own assets and/or freedom to pursue a fake lawsuit on your behalf. The justice system is subject to Sybil attacks like any other system.
Again, no, because courts don't as a general rule treat with "bogus" claims. If you try to lie to get a subpoena, the other counsel calls bullshit and the judge agrees. This just isn't a thing. This is another angle of the "Hackers Think The Law is a Computer" disconnect. People don't try to hack the courts like this because they tend to get disbarred if they try.
My personal experience is inconsistent with your broad confidence in the justice system's resilience to abuse, and in fact is one of the main reasons why I retired from active practice as a litigator. I've found that concepts like "bullshit" in civil law have many shades of gray, especially when you're dealing with a genuinely angry client seeking justice.
If your experience is closer to the truth, then maybe the tech industry should retain lawyers to redesign our security systems!
This is especially effective if you're a powerful person or corporation and can find a litigant willing to sacrifice their own assets and/or freedom to pursue a fake lawsuit on your behalf. The justice system is subject to Sybil attacks like any other system.