Knowing the science can keep you from making mistakes such as significantly raising the temperature and pH in a tank with measurable ammonia (toxic un-ionized ammonia will increase by 3-6 times even though the API ammonia test which is sensitive to both less toxic ionized plus unionized ammonia will show the same test level).
Knowing the science won't help you know what size tank you need, how much live rock, what species are compatible, what temperature is best, what the best Ich cure is, how much salinity is optimal for your fish, where to buy at good prices, or what you should expect to spend on your setup. This knowledge comes mostly from experience.
I find knowing the science sometimes makes me crazy frustrated because science depends on data, and there is more bad data than good data out there in the blogosphere. I sometimes read for hours, get nowhere, and can't make a decision. That's where having very experienced fish keepers like PP and RTR to consult is as valuable as gold.