The cases you're talking about (the non-porn ones) happened many years ago. I mean Tennenbaum was 10 years ago, Thomas was about the same. However, the main difference is that instead of just straight suing, and then offering a settlement and suing, here they'll sue (john doe for ex parte discovery) then offer a settlement, but then NOT sue again. They go out of their way to not conclude the litigation.
The Patel case in Georgia shows that perfectly. They Doe-sued in DC (in the court of former RIAA lawyer Beryll Howell) to get the info, then sent a demand to Patel here in GA. When he didn't pay up (or reply), they filed a case in Georgia. Then when he didn't respond, they filed for a default judgement which they got. However, within a week of filing for and getting the default judgement, Patel hired a lawyer, who then filed asking for consideration to litigate with a reason for the non-response. Since it was timely and courts prefer litigation over a default, it looked like the court would re-open the case. So Prenda dismissed the case before the judge could set aside the default.
If there's one thing that get's a judge's attention, it's a case where the plaintiff's are so eager, they push for a default judgement, but when they had it and might lose it, they'll actually dismiss the case rather than risk losing. It means they knew they had absolutely no case, and judges (especially Senior (and former Chief) Judge O'Kelley don't like that at all. (He also doesn't like the internet, but that's another story, and probably related to the fact he was appointed to this court by Nixon in 1970)
but that's why it's extortion. There's no good-faith effort to litigate to right a wrong. it's litigation purely for the purpose of identification, and to collect money from those who are apt to pay up, or who ignore it and hope it'll go away (and so get defaults). Demanding money with threats is extortion, because threats are all they have - they have no facts.