It's not really a dead genre per say, I agree it's not as popular as it used to be, however i do agree that most MMO's are not as good as they used to be and many lost their magic, but the genre is far from dead, Runescape(both 3 and old school) is actually growing in popularity , world of warcraft while not as big is still a very popular game, warframe has a very big player base and other than these that i am familiar with, there are thousands of games with die hard player bases that are still being played and updated to this day! (toram online, ever quest, black desert online, ultima online, final fantasy etc.)
In my opinion MMO's original selling point whas the multiplayer part(the player interaction) but nowdays people have so many ways to talk and meet each other so that aspect of them is kinda gone resulting in many games failing to attract new players to the genre!
Adventure quest is goated! I unfortunately never heard of Dragon Fable however ;_;