In the 90s, due to a misunderstanding of how indexed color displays worked, it was popular to prefer colors with hex triplets with their digits duplicated (i.e. #03F is a shorthand for #0033FF) in steps of three (0 3 6 9 C F), or, expressed as factors of 256: 0, 0.2, 0.4, 0.6, 0.8, 1.
These colors weren’t really any safer since they’d be double-quantized on different palettes. Thankfully this dumb “web safe colors” myth died when 24-bit displays became affordable.
For all you retro- and permacomputing lovers out there, the traditional VGA/CGA colors instead uses these steps: 00, 80, C0, FF. That creates 64 colors but they selected sixteen from them (so it could be indexable by four bits). Out of these sixteen, blue (#0000FF), navy (#000080) and purple (#800080) are good candidates for link color. You want it readable with dark foreground text, you couldn’t go gray because the background was gray (for some reason), you want two colors that sorta match each other but are different. Out of these three, they selected blue and purple.
These days, the WHATWG recommended colors are #0000EE blue and #551A8B purple, but they don’t explain why.
For the light mode version of my own homepage, I wanted something close to the retro original, both for fun but also to make it clear that the links were links. My first page on here was what’s now the /about page and it was just a bunch of links to images! (Writing came later.) I wanted it to be obvious where you were supposed to click and I wanted a different “visited” color (even though that was out of fashion at the time) since people were asked to go through a huge list of links and it would’ve been cruel not to.
But why did I go with #321eb0 blue and #9c1eb0 purple and not the retro originals? It’s to match the Classic Mars color (#B0381E) of my thistle logo that I’ve had for twenty years. I created the Cilce Palette by stepping through hue and value in fixed steps, calculated to fit both that red and another tealish color I once used as an accent color for a linguistics slideshow. I wanted something that looked close enough to the real thing but still looked great with the thistle.