Earlier quoted context omitted.
What functional improvements are fundamentally incompatible with the "old" protocols? Longer lines could have been supported with a minor protocol revision. Giving customers the freedom to use clients that don't render images, or markup, is actually a positive. I setup Mattermost for my company. The deciding factor between Mattermost and IRC was effort to get non-technical users a nice GUI. Functionally, IRC would ha…
it feel a bit biased when you say that IRC could have a protocol bump, but you wouldn't make the same modifications to hide pictures in Mattermost. Additionally not being able to share images as a feature? I guess everyone will do the three step upload to imgur first. In my world - if I could get away with less different clients I would. It makes it a nightmare to support.
Imagine this:
You have a bot in your channel that accepts an "upload-image" command followed by a base64-encoded string representing an image (or a series of these commands if line-lenght is limited, I'm not sure about this part of the IRC protocol). The bot checks that the image is actually an image (to avoid weird injection tricks), saves it on the server and returns a link you can share or sends the link directly to the user/channel of your choosing.
This can be automated with a irc client, of course. Users using old clients will receive an actual link, users of this supposed new client see a clickable preview of the actual image inline.