The best design system around[0] operates entirely in the open. You can look through the history, discussions, PRs, framework-specific implementations and see why it's geared the way it is - and why it's incredibly successful.
For designers who wish to take part and contribute to this design system, does that mean they need to learn how to install nvm and all those requisite steps?
You can contribute by responding to the discussions in the backlog[0], by improving the actual distributed styles and code[1] or suggesting improvements to the documentation in the link I posted above.
Bigger changes need to be backed up with user research, evidence of user needs and accessibility reviews and checks.
[0] https://github.com/alphagov/govuk-design-system