All cherry switches FEEL linear when you're typing fast, and Cherry MX blues are by far the smoothest of the crop.
Put a large comforter over an MX Blue board and an MX Black board to muffle the click sound.
You'd see that in actuality, BLUE is a much less fricative switch because the blue stem is only going past the very loose white nylon slider, whereas the entire black stem is in contact with the housing and the leaf spring, much more friction.