In tailwind, you have a config file. You can just change the variable in the config file to the colour you need to change it to and it changes globally.
I think the big shift started to happen when people started to say, let’s treat CSS like code and what would we expect of good code, and then all of these CSS Sacred Cows were then seen in a new light. The biggest of them all for me was ‘naming things are hard’, traditional CSS implies naming your classes is easy, and for a once off example it is always easy, but that approach is a lifetime commmitmnet to generating names on names just to add styles and this adds a naming things complexity burden that until recently has just been a generally unacknowleged invisible cost.