I do agree with you that the written rules weren't necessarily clear at the time. However, baseball (for some reason) has a LOT of unwritten rules. If you as a batter on second base yell, "curveball coming" to the batter at the plate, well, that's not against any rules. But the batter on second base will most definitely get a fastball to the back his next time up.
Seems like 100% of current and former players also have agreed for years that using technology to steal signs is against the unwritten rules. Now the written rules are clear on this.
Another unwritten rule is that there's some sort of clubhouse code, where you don't rat out fellow baseball brethren. I totally get loyalty but personally I think this rule is stupid as applied to the astros situation. This is why some people were/are mad at Mike Fiers.