a:visited styling is very limited and computed styles are not reported properly

[RonnyO]

Due to privacy concerns, browsers limit the way a:hover states can be styled, and computed styles report normal state, to avoid leaking browser history.

More information:

• MDN - Privacy and the :visited selector
• Impresive Webs - Limitations on Styling Visited Linkslinks/

[mdo]

If anything this should just be a tip like:

Don't set :visited links

The :visited pseudo-selector isn't necessary in your global link styles. Simply styling a will address the styles for all relevant use cases.

Super quick pass at that, but I think that one makes sense more than privacy concerns.

[cvrebert]

Erm, should that be "Don't bother"?

[RonnyO]

These are two different things. I believe the sneaky behavior of :visited is part of the reason why almost no one uses it anymore, it's confusing.
Clearing that up while reinforcing the importance of styling visited links where it makes sense can be really helpful.