I've found myself to be okay with either colouring text or not at all, I just find that most people tend to like it for aesthetic purposes. I always found colour helps break up long posts and in a way it kinda reminds me of video games RPGs where your party members are associated with a colour, which I think is kind of fun.

On the flip side, it makes formatting in collabs a pain in the ass, especially when the colour is a code instead of a word. That's a big factor for me not wanting to deal with it sometimes.

However, which it comes to formatting character sheets, I always use coloured headers. It makes it look great and helps visually distinguish bullet points from supporting text, and when combined with bolding, italics, and underlining, it helps to visually break up subsections effectively.

A rule of thumb for anyone, I feel, should be use colours that are easy on the eyes with RPGs' background. If you have to squint or highlight text to read it, change that shit.