In macOS Monterey and later, you can select text in screenshots and other images in e.g. Preview.app. When people paste screenshots of user interfaces etc. on Mattermost, and I want to copy & paste some text from it, then I have to first right-click the image and select "Copy Image", then switch to Preview.app, paste the image there, and then select and copy, and switch back to Mattermost to paste the text. This requires more steps then necessary, and is not very discoverable, leading many to simply not know they can copy text from screenshots.

If one limits the feature to the desktop client on macOs, it seems like it´d be a few lines of code, and it´s done. See https://developer.apple.com/documentation/visionkit/enabling_live_text_interactions_with_images/#3971774 . Doing it in a general for all clients could be difficult, but I don´t think that that should block the feature on macOs.