About 1 in 12 men and about 1 in 200 women have some kind of color vision deficiency. Most commonly they have difficulty distinguishing green and red*. The default color choices essentially never account for this.
* Yes this does mean traffic lights are a problem. Fortunately for Americans, the red light is either far left or on top.
As long as the information is communicated other ways as well, the colour is just a helpful thing for discriminating the messages and the loss of it by someone that’s colour blind, using a terminal with a configuration that doesn’t allow colour, or even just is sitting somewhere the sun is shining on their monitor and making colours hard to differentiate is… inconsequential.
Except that a color bind person doesn't see monochrome, they see color, but perceive it differently. So the color palette problem isn't confined to only red and green, but also to other colors, because the spectrum as a whole is distinguished differently. Also, red/green color deficiency, while the most common, isn't the only kind of color blindness.
This is an argument against using 256-color or true color though.