The implication is that a secret is being revealed, possibly a dark secret to worry about. But FB and others put content in alt tags for people to read when the

The implication is that a secret is being revealed, possibly a dark secret to worry about. But FB and others put content in alt tags for people to read when they can’t see the images (for example die to blindness), it is much less dramatic to “reveal” something that was intentionally put there for people to read.