I am mostly assuming based off of my personal experience, Someone shares a link or photo, and everyone responds. User-testing would be fairly telling here, thou

I am mostly assuming based off of my personal experience, Someone shares a link or photo, and everyone responds. User-testing would be fairly telling here, though the difference would mostly be "Should we show the comment button automatically or not?" A message could become a post just as easily as users currently use "reply", instead they could "comment". Honestly in situations that use a "reply icon" the icon could even remain the same. So yes, I think that media + manual is close enough to perfect.