I think he just means using a internal sd reader....which yeah will work fine in most cases as long as the reader is compatible with the 3DS nand, up until I did my first 2ds which wasn't compatible with my laptop reader that is all I was using
the compatible reader lists are there for people to be able to go buy one that works if theirs doesnt, I wouldn't go suggest someone go buy the same laptop as me to read/write their nand XD