If some people can and do paddle comfortably in 30 or 35 knots winds (uncommon maybe), I assume that we KNOW this, or they KNOW this because somebody was carrying and using an anemometer, and not just guessing. I assume that we are not just taking someone's impression of what the wind speed, wave height (always a puzzler!) etc. was, as a substitute for an actual datum. Now, with GPS, kayakers can get a lot closer to accurately measuring current speed also. My point, again, is that it is better to know, and relatively easy to know, with an anemometer, how hard the wind is blowing, really.
Here's the ideal scenario: superpaddler A goes out with his anemometer, and determines that he is happily and safely paddling in 30-knot winds. Less-experienced paddler B, also armed with an anemometer, visits same site, holds up his anemometer on the beach. It reads 30 knots. He looks at the water and quickly realizes that 30 knots of air, and the subsequent waves, are way beyond his abilities. Thus, both parties actually know how hard the wind is blowing, and can make more informed judgments about how, when, where to paddle.
Frequent use of an anemometer helps to calibrate our subjective impressions of conditions on the water with an actual, measured wind speed. Like a thermometer, or a ruler, or a chart, or a compass, an anemometer is just another way of quantifying phenomena such that people can accurately evaluate the magnitude of phenomena and then communicate with one another.