Have you never implemented a design yourself, and then found that when you looked at the results as a whole, it didn't work quite as well as you hoped from the original concept work?
Have you never A/B tested a site and found that varying colours made a difference?
Have you never developed a site with some colour scheme and later found you needed to extend the colour scheme, perhaps to incorporate a new product or service being added to the available range?
Having a colour scheme that is set in stone early on sounds like one of those idealised things that sometimes just doesn't work in the face of reality.
I'm currently building something that has mild themes for fonts, colors and some margins (and is build on top of a SCSS framework, but that wasn't my choice), without color variables it would be a pain...
But we've all been in a situation where it's got 'that far' and someone more senior has got involved and done exactly that. Plus, it makes designing in the browser waaaay easier.
Have you never A/B tested a site and found that varying colours made a difference?
Have you never developed a site with some colour scheme and later found you needed to extend the colour scheme, perhaps to incorporate a new product or service being added to the available range?
Having a colour scheme that is set in stone early on sounds like one of those idealised things that sometimes just doesn't work in the face of reality.