Board Thread:Technical Updates/@comment--20180108232631/@comment-27345308-20180109150834

You could've hotlinked an avatar before too, if it were suffixed with. On most wikis I believe you could've hotlinked Vignette images before, yeah. I know the code repository pull requests aren't the most trusted source of information related to community team decisions but there's the quote for the pull request related to this change: "This is so we can deprecate hotlinking external images and allow users to hotlink images from personal or scratchpad wikis."

- Grunny

Ultimately I believe they did this because of HTTPS support and potential attempts at implementing a Content Security Policy.