I have personally been sued frivolously. After 6 months of stress during which the plaintiff decided to fire a lawyer and started to harass my attorney and expect them to spend time explaining the law (time for which I eventually was billed), we decided to settle. The plaintiff was supposed to pay me $6000, but decided to reduce that amount to roughly half. I just didn't have any energy to go to small claims court arguing that she still owed me the rest of it.
Had their initial lawyer been on the hook for a frivolous lawsuit, the whole thing would probably have never happened. Rather than getting all of the info, they were more than happy to only get one side of the story (truncated email threads, not preparing them to answer to a discovery packet and so on) and to get their money, only to find a way to bailed once they realized it was not going to be worth it.
Another thing that I found absurd is the fact that "reasonable attorney fee" doesn't seem to cover more than half the reasonable fees. My lawyer suggested filing motions to compel and/or motions for sanctions, but also warned me that it would cost me more than what the judge would award me for the fees. And of course, nothing for my time...