They would claim grand things like having solved the issues with continuations and delimited continuations, distributed process migration and a whole host of other very hard problems that haven't been solved in the past. I would ask their founder: "right, so you know that delimited continuations have problems with accidental captured scope, they run poorly on the JVM, how did you solve this, have any papers I can read?", and all I ever got was that Clojure, immutable data, X and Y would fix these issues and you just had to wait and see what they were cooking up.
That's when I knew they had no clue what they were doing. I'm all for pushing the boundaries of tech, but if you're doing something attempted many times before, you at least need a good elevator pitch as to why it's solved now.
I think a great example of this done right is Rich talking about Clojure. People would ask "isn't immutable data expensive to reclaim and allocate". And his reply was always that the JVM's GC was just that good that the benefits to be gained from immutable data outweighed the marginal performance penalty of the amount of garbage collected. What changed since the old lisp days? Well we now have GCs that are super fast and JITs that can optimize dynamic code well.
That's the sort of laser focused vision I never saw from Red Planet labs. You gotta get that problem statement and the solution out early, refine the elevator pitch and be able to articulate to people who know what they're talking about how you're going to succeed where others have failed for decades.