And the web suffers from all sorts of accessibility problems because developers don't take that into account. Native applications (and I'm not talking about Electron) is a better example -- Microsoft and Apple have taken accessibility concerns into account and created interface toolkits that aren't a rainbow of colours by default and which users can easily customise one colour scheme in the systems control settings to affect all native applications.

Using 256 or true colours in console applications break the terminals ability to apply the user-defined colour palette and that can bring accessibility issues with it (as well as being a little annoying for anyone who happens to prefer non-black backgrounds).