Why all blink tutorials use 330 ohm resistor When I do the led calculation I found 150 ohm resistor is enough for 3mm red led. If so why all arduino tutorials, like this one, are suggesting 330 ohm resistor?

I assume V = 5 Volt, diode forward voltage = 2V and diode forward current 20mA
150 Ohms may be "enough", but it's often still far too bright, so many tutorials keep a lower limit of around 10mA to help the LED live longer without affecting the application. 

You'll probably find that red LEDs are still visible at 1mA and a 330 Ohm resistor with a 5V supply will give about 8.5mA (assuming a 2.2V drop), which is plenty. 

It's really a "lazy" choice that will work well in "most" situations.