User blog comment:Rappy 4187/Technical Update: March 14, 2016/@comment-5558012-20160314222356

Thank you for the image update in threads. Some people either don't know how to resize an image or fail to realize smaller screens have a smaller comment area and the large images don't work everywhere.

Edit: I took a glance and this update doesn't look like it solves the issue of size in regards to an image generated by external URL.