It's an interesting idea, but I think you're trying to quantify what are qualitative assessments. One person's impression of what is 'good' for wakestyle might be completely different than another's. For example, a lighter rider might prefer a more flexible board where a heavier rider may prefer something stiffer, or vice versa.
It all comes down to personal preference, and I'm unsure of the utility of rankings even within specific categories (unless you get *very* specific--which creates its own challenges). Just because a certain board is found to be 'best' for a certain discipline doesn't mean it will be right for my application. The number one ranked freeride board might suck for me because my spots have tons of chop.
Further, what happens when you try a new piece of equipment and it is your new favourite? Has your old favourite gotten any worse? Of course not; but maybe your preferences have changed, or maybe the new item is simply better for your particular needs.
All the negativity aside, I *do* see the utility in something like an OkCupid for gear. You fill your profile with your personal info (weight, height) and the types of conditions you ride in (different sets for different locations). You then provide ratings on how your gear performs in those conditions. So when it comes time for an upgrade, you could find what works best for other people of your size in similar conditions. This is of course orders of magnitude more complicated than what you initially suggested and would require a critical mass of dedicated people to make it useful.
Imagine all the cool data you could derive though! Stuff like, "People around the great lakes like kites with a lot of depower for their gusty frontal winds." or "Heavy dudes in Hood River prefer directionals with a lot of rocker."
Hopefully that contributes something to the discussion.