Hi Dominique,
You suggest following the Wikipedia example. How different is that from simply reverting moodle.org forums to the previous state of things, i.e. before they introduced that bold attribute which had me whining ?
On MDLSITE-6897 Jessica Gramp added this comment:
There is a suggestion to use underlined text from a user who is finding the bold text distracting. See: https://moodle.org/mod/forum/discuss.php?d=441430#p1776061. I also now have concerns that (when looking at this with my Black and White Chrome extension, that strips all colour from the page) you cannot tell what is bolded text as a heading / title / emphasised text style and what is a link in some cases. Underlining the hyperlinks would resolve this issue.
The Black and White Chrome extension is one of the ways to test what a site looks like for those visitors with colour blindness, more specifically monochromacy/achromatopsia. See also this page.
Interestingly, if you visit websites devoted to the question of accessibility for colour blind visitors, you'll find that their links are systematically underlined.
Coming back to Dominique's suggestion, i.e. following the Wikipedia example, I'm afraid visitors with monochromacy/achromatopsia are not able to view its hyperlinks (other than mouse hovering or keyboard focus). So the question remains open...
Just a thought which might make everyone happy: why not offer moodl.org visitors the option to switch (in their Profile) to an accessible theme (not sure if there are any such themes at the moment)?