Most of the color names come from X11 rgb.txt which was not exactly "designed" to be anything and also many entries assume RGB color space of some particular Unix workstation which was decidedly non-sRGB (eg. using significantly different gamma curve).
Worth watching the Technology Connection video on the colour Brown [1]. It's a strange colour that only really exists when placed in the context of other colours, not something that can really be produced by a pure RGB light source, which explains why the CSS Brown colour looks red.