Just in case you don't know, several modern IRC clients will automatically fetch links posted in the channel and, if they are images (or even things like YouTub

Just in case you don't know, several modern IRC clients will automatically fetch links posted in the channel and, if they are images (or even things like YouTube videos), display them inline. I don't know if any of them support automatically converting pasted images to links, though; it sounds sinple enough that I wouldn't be surprised if at least one did. Of course, what you mentioned is only one of many things that Just Work in Slack and are at best a pain on IRC, but still.