Previously, when the "Add comment" link was disabled for a logged-out or low-rep user, it carried the notice "Requires an account with 50 reputation". There was some discussion on improving the aesthetics of that notice, but now it seems to have disappeared completely.
If I visit a Stack Exchange question when not logged in, I see the text "Add comment" below it, but it does not appear to be a link and carries no notice about why it is disabled.
This looks confusing for a new user. The "Add comment" text looks like it should be clickable, but there is no explanation why it doesn't work. When hovering, the cursor turns to a text-cursor, rather than a pointer-cursor, so it doesn't even appear to be a link that's nonfunctional, it just seems to be non-linked text.