I'm not sure about this, what does it bring?

(replying from email here since im on the morning commute to work)

I'm not sure to be honest. I noticed it on discourse first, and i think
other git forges do it too. It gives other people some info on the state of
the poster. For example, i cant provide an image at the moment since im
replying by email, and that also means i may not be able to review PRs or
make quick fixes. What i can do is "ack" so others know ive read and am
aware of the discussion.

What do you think? A UX person may be able to explain it better XD

One way it proves useful, on GitHub, is to indicate to other participants, "This user may not have seen all of the "auxiliary" content in this conversation."

Someone following an issue only via the email notifications doesn't get any of the embedded images or attached files in others' comments, can't see any tags placed on the issue or any reactions people have left on comments, and if any comments have been edited after posting, they may only have seen the original version.

(In fact, for the benefit of email participants, I try to remember not to make any significant after-the-fact edits to my comments. If I need to correct something in an earlier comment, I'll typically use a slightly roundabout process to make sure it reaches everyone who saw the earlier, incorrect version...):

1. I first post the correction in its own, separate new comment, referencing the earlier comment which contains the error.

2. After the correction is posted on its own, I'll go up and edit it into the original comment.

3. Finally, after the original's been corrected, I'll go back down and delete the now-superfluous correction. (Which by that point has already been sent out as a notification email.)

Someone following an issue only via the email notifications doesn't get any of the embedded images [...] in others' comments

That part of what I wrote was wrong, at least in terms of GitHub. Embedded images are sent through in email notifications. (Though any other file attachments won't be, I believe.)

It's actually the other direction that's more of a concern. I often have to remind users replying to GitHub issues by email that they can't attach images or files in their email, as they'll be discarded before posting. The only way to include an attachment in an issue comment is via the web interface.