The challenge with roman numerals was definitely computing with them and really "thinking with them". Abacuses helped, but it was still a poor UX in many ways and it took lots of training & practice to get familiar.
Algebraic notation also requires training & practice but has a much quicker learning curve. Almost every literate adult uses equations in some form or another on a weekly basis. Both the medium (pencil & paper) as well as the representation (algebraic notation) were critical to this (as well as other things like education system / literacy, etc).
The benefits & disadvantages of different representations is massively understudied and misunderstood. Data visualization, semiotics, and some other fields focus a bit on this but still fall short in many ways.