Some loved ones of mine are lawyers and went through this or saw it firsthand.
Things started with the crash of '08. Lots of people went back to school, including law school. That frequently happens in an economic downturn. The thinking is, you should go to school when the job market is weak, because things should be picking back up by the time you graduate.
Problem #1: The flood of law school applicants made admissions more competitive, so a lot of people got into worse schools than they could have.
Problem #2: In law, your career prospects depend heavily on what you do during your summers. Most law firms and courts cut their internships massively -- and sometimes entirely. So, you had too many applicants applying for WAY too few jobs. And if you can't get a good internship, you'll be WAY behind in the job search.
Problem #3: Many law-related fields lag the economy. So, even though the economy did start to recover in 3-4 years, that was when law jobs were hitting their low point.
In sum: A massive wave of law graduates -- most of them from worse law schools than they could have gone to, and with worse internship experience than they could have had -- hit the market at a time when almost no one was hiring. People who went to the top law schools got decent jobs. Everyone else got scraps. And many of those who did get jobs were treated poorly by their employers because, hey, there were plenty more applicants where they came from.
It was a meat grinder. I have HUGE respect for anyone who did even an okay job under those circumstances. And while I can't condone suing a school over lack of job prospects, I can certainly understand the frustration.