The main thing I do in WoW is quest collecting/Completion, its a lot of fun, it can be a bit frustrating at times too, but one of the things we encounter the most is people not really understanding what it means, and sometimes there is a design decision by the devs that didnt take quest collecting into account, which we understand as its a less common playstyle, and there may not be any on the development team at all,
so the point of this thread is hopefully to provide some general context of quest collecting and hope it helps players and devs understand the playstyle 
The two biggest categories to think about when it comes to quest collecting is Character vs Account collectors
Account: Account wide quest collectors aim to have as many different quests completed by any character on their account, the total amount of quests for this is about 25% more, but is generally considered the more sane way to go about quest collecting.
Character: Character wide quest collectors aim to have as many quests as possible completed on a single character, the degree to which you do this depends on the person, the base level of this is just completing every quest you can find normally, this eventually will lead you to loremaster, and most other quest achievements along the way,
Additional paths some of us take:
-Include bonus objectives (They are quests)
-optional changes like swapping covenants to do every campaign variant,
-doing things in particular order to avoid missing breadcrumb quests
-Party Sync in order to do mutually exclusive quests, such as multiple breadcrumbs leading to one quest, or do the normal and alt char versions of a questline (DF Adventure mode for example)
-Swapping Professions to do the quest chains that are exclusive to particular professions (this is generally only done by those of us who dont collect recipes)
-Race changing to do race exclusive quests, (some starting zones for example)
-Faction changing to get the other faction quests (See footnote on this one*)
*Faction changing is considered highly dangerous, to the point a vast majority wont risk it, when you swap to the other faction, alliance to horde for example, most alliance quests have their credit lost, but not all, after finishing horde quests and swapping back to alliance, you will regain MOST but not all alliance quests you have previously done,
its a lot of extra work, but you do end up with more quests in the end, you will end up doing several questchains that are bugged to always lose credit several times (for example Ive had to complete the return to lorderon questchain at least 4 or 5 times on my character.
Things we would like the devs to remember:
-When re-adding old content, there are those of us who are hoping and hoping for old quests
-There are people who collect breadcrumb quests
-Quests that you can be permanently locked out of completing, is 
-really the most important one is, please remember quests are something that is collected
I don’t want to make this post so long that people wont read it so im going to leave it here, I hope it can help folks understand this playstyle more