It would be nice to know what quests are available & unavailable, using such addons as Questie are useful for finding new & completing quests.
Occasionally there are quests that cannot be given by an NPC, this could be a link quest has not be completed or a level not met, class requirement, questie is not the right version, etc. There are places on the server that the quests are just not simply loaded in, like in places in Felwood or a lot of Silithus.
I admit I'm still pretty new to WoW but I know the client is 1.12 but the servers are different versions with certain quests enabled or disabled.
What I am suggesting is a Quest Master List here on the forum or website for each server showing enabled or disabled quests or quest chains.
I do not know of the cons of doing this but if there is one or more, it would be nice to know. Another pro is the list can be a place to signpost people who keep asking or even whine about why something is not there on the server but another resource being addon or wiki is saying otherwise. Like the quest could have a note saying, "Disabled, fixing bug" or "Coming in future path," etc.