Problem is, many quests are changed or even outright removed from the game as time goes by and so this would cause issues for such achievements, as then where do you then draw the line at what would qualify towards the achievement? Only main scenario quests? (We already have main story quest achievements so this is redundant). Sidequests? Those are the ones most likely to be altered or removed. Just reward an achievement for amount of quests done in a certain area? Technically we already have that, but not by area.

Also expansions tend to add even more sidequests to existing areas which could potentially add even more complexity to implementing such achievements.

FFXIV 1.0 did have something like this, but those achievements are no longer obtainable due to how quests are handled being changed in ARR and many of the areas offered no longer plain existing in ARR, like Camp Emerald Moss.

It would be a nice thing to have, but sadly, I do not see SE adding such a system due to the above reasons.