It is similar to why we chose gold to use as “gold” as humanity. Not all elements are suitable to be used as a store of value and physical currency. Let’s look

It is similar to why we chose gold to use as “gold” as humanity. Not all elements are suitable to be used as a store of value and physical currency. Let’s look at the primary and secondary colours. Yellow: Bad contrast. Red or Green: Action colours, would be bad to see them everywhere. Plus there might be accessibility concerns. Orange: Mostly used as “Not as urgent as red”. Purple: Not as neutral as blue, yet it is the second best option, that’s why visited hyperlinks are purple I assume. It is the logical choice. We are left with the colour blue. Also, a plus that it is a primary colour; I would assume it is easier to display primary colours in earlier tech.