Mono - alone, single.
Monochrome - an art technique using different shades of a single color.
Being a single in a sea of complementary, analogous, and triadic can be lonely. There are benefits to being a single in this same sea though, it allows you to not be anchored to any other shades.
When starting branding and logo development sometimes being tied down to other shades limits your options from the get go. Staying monochrome for the beginning of branding development or even the entirety of brand development is simple but effective. When you start in monochrome you can analyze the nature of the essential design elements before you are swayed towards a certain design purely based on color attributes.
