"Guide" for the race committee is different from making it official by putting it into the sailing instructions. For instance, in the case of maximum wind limit, 25 knots might be fine on a flat sea, but 18 knots might be too much in high, close-together chop.

And on the light side, 5 knots (or even less) with steady direction might be okay on a flat sea and no current, whereas you might need at least 8 knots if you are also dealing with chop and/or current.

I would agree that it would be helpful to race committees to have detailed, suggested guidelines to assist them in making their decisions -- but those guidelines should not be law. The final decision should be left up to the race committee, and it should not be protestable. IMHO

P.S. I see Wouter beat me to it, regarding sea state.