The problem is that Heroku made claims about their architecture and subsequent performance characteristics that were flatly untrue.
The further problem it looks as if they knew the claims were untrue.
These are not matters of internal consideration. They cut directly to the heart of the Heroku marketing material: "Write for our platform, our expensive secret sauce will make your stuff linearly scalable."
In which case people expect that it will be linearly scalable. Not exponentially anti-scalable.
The same can be said for EC2. "Amazon EC2 reduces the time required to obtain and boot new server instances to minutes, allowing you to quickly scale capacity, both up and down, as your computing requirements change."
If my instances don't launch "quickly" or I've designed my app in such a way that it isn't 100% linery scalable I can now sue Amazon? You can't sue heroku for their marketing speak.
You can sue anyone for anything, success is not assured.
That bit of pedantry aside, Heroku led people on to believe that their queueing backend was intelligently distributing requests to nodes. Rather than randomly.
You are not allowed to argue this, as Heroku themselves acknowledged it!
Furthermore, they blatantly lied about it. From the rap genius article:
Heroku claims that though they received reports of unexplained latency over the past couple of years, they weren’t able to figure out the request queuing issue until they read the Rap Genius article. But there is evidence that Heroku knew about the problem for more than 2 years.
And the conclusion, also from the same article:
Based on Heroku's response so far, it appears their approach to fixing the problem is, “We promised you intelligent routing, we delivered random routing (which is worse than intelligent routing), so we're going to change our documentation to make it clear that we're only promising you random routing.”
This works for future customers, since once Heroku makes these documentation changes, everyone who signs up will understand exactly how routing works. But it does nothing to address the time and money that existing customers have spent over the past few years. What does Heroku owe them?
Who's to say random routing doesn't qualify as "intelligent"? What if random routing is the most efficient routing schema for 99% of their users? Trying to sue because "intelligent" doesn't mean what you think it means isn't going to be very successful.
I don't know how "intelligent routing" can be defined to mean anything. It can be interpreted a million different ways. This is probably one of the reasons why they used it in their marketing because it sounds cool and is a generic term that could be applied to anything.
I don't see much of anything in a lawsuit unless specific metrics related to SLA's that were agreed to were broken.
The documentation used to say that requests were routed to the next idle dyno, but the behaviour was silently changed to be random distribution, which is substantially worse for the customer. There seemed to be previous cases where Heroku were aware of the discrepancy but didn't act to fix it.
The further problem it looks as if they knew the claims were untrue.
These are not matters of internal consideration. They cut directly to the heart of the Heroku marketing material: "Write for our platform, our expensive secret sauce will make your stuff linearly scalable."
In which case people expect that it will be linearly scalable. Not exponentially anti-scalable.