Which is a problem. If that form were legally sound and the case solid, then there shouldn't be an issue...but, you're correct that there might well be. The legal system is somewhat deficient for the ordinary citizen. Or maybe I should say that the other way around.
From a practical perspective, though, there's just no way to litigate 100MM+ individual cases, which is why this will be a class action that will be settled. Lawyers will win and claimaints will see very little per.
The thing is that the potential damages could, in theory, far exceed the total value of Equifax or their ability to remunerate. True justice, then could never be fully served. That brings up an interesting point about the outsized risk some companies represent, with very little attendant oversight or regulation.
In general we seem to be asleep at the wheel. Whether it's Russian hacking, recent revelations about powergrid infiltration, data breaches, or all manner of online and technology-based fraud, there seems to be a vast under-appreciation for the stakes. There's talk about it, but relatively little progress is being made.
An action under the FCRA may be brought in "any other court of competent jurisdiction", carries statutory damages of $1k for willful non-compliance, and allows the judge to assess arbitrary punitive damages. Given that you're likely the only person talking and that you'll be describing systemic issues which affected 143 million Americans, I think you should just ask the judge for the max and see what he says.
HNers are, by the way, likely to be well-served by small claims courts, just by dint of education, organizational ability, and ability to perform professionalism.
[+] 15 U.S. Code § 1681e(a) -- "Identity and purposes of credit users" requires "very consumer reporting agency shall maintain reasonable procedures designed to avoid [unauthorized disclosure of information]" Your argument, informally because small claims court, would be "If your procedures allow you to disclose credit information on 143 million people, your procedures are per se unreasonable."