The first times I went on the Haunted Mansion at Disneyland, people in the room would ALWAYS quote along with the "FIND... A WAYYYY... OUTTTT!" portion- I think every time this happened. This was about 1998 or so. When I returned in 2010-ish, nobody did. And in Disneyworld in 2014, nobody quoted anything, either. Then I found out on the forums here that this behavior usually gets a lecture from Cast Members these days, with people saying "stop talking" or something in non-CM lecture voices.
So when did this start? I actually approve of the practice, though I find it interesting- is it a reaction to too many repeat guests/AP Holders quoting the stories and ruining it for everyone? Did new Disney fans complain to City Hall too many times? I'm curious.