I think you are misleading investors that investing is Provably Fair is a bit manipulative.
These games are only Provably Fair proveable fair to players, these investing sites are currently not Provably Fair to investors. (besides maybe PF to you and devan, but it is definitely not PF to me if I invest.)
Investing is not Provably Fair by math. Period. Please consider changing this.
The full dot-point in question is:
Neither bustadice nor its auditor can undetectably cheat by predicting future rolls. Assuming you trust the two not to collude, investing becomes provably fair.
which states the caveat pretty explicitly. Although I actually agree with you in that provably-fair is the wrong term for it. I'd probably write the copy as "Assuming you trust the two not to collude, investors are given additional protections against cheating" or something of that sort