As an avid collector, one of the things I try to accomplish is to do all quests possible. I think there are two improvements that could help quest completionist.

1 - Track already completed repeatable quest (daily, world quest, holiday, etc) For now is not recommended to let active the quest filter because there are so many quests that reset daily, weekly, etc. but for some, like me, it could be interested to complete every one of these quests at least once. So with this option active only completed non-repeatable quest and repeatable quest that had never be completed will show in the addon list.

2- Account tracking option for quests. Similar to the previous, some people could be interested in complete every quest and doing just once with one character is enough, but there are some quest that requires multiple characters, for example, if I completed all Horde and Neutral quest of a zone and I just want to complete Alliance exclusive quests with another character, the same for quests exclusive of some races, classes or professions. This even allows completing breadcrumbs quests.

This would mean the addon should keep track of every quest completed by characters, especially the non-repeatable ones can't be collected retroactively, but some other quest addons keep track of them and the maybe data can be imported.

1Collectible quests and time-gated repeatables (daily/weekly/etc vs true repeatables like questID 9217 "More Rotting Hearts" in ghostlands) work differently from each other. One-time quests in zones are indefinitely marked as completed, while any kind of time-gated repeatable typically has a completion event recorded by Blizzard that gets removed after a period of time. For us to record if a repeatable quest has been completed at least once, it would require client-side caching of questIDs on completion. While this is doable, the cache can be reset far too easily so it wouldn't provide a stable/consistent long-term solution. If I understand what you're suggesting, it would effectively be a sort of "completion counter" on repeatables to record the number of times they've been done?

That said, if you have Show Incomplete Things checked, you can disable that option. Quest tracking does not depend on it so you'll still see collectible quests but your ATT list won't show optional/missable breadcrumbs or repeatable quests unless they grant something collectible (e.g. achievement criteria, collectible items, etc).

Account-tracking for quests was recently added in commit d740062 with the caveat that this will cache completion states across all characters you log in to, so your ATT list on a brand new character will show quests as having been collected if you have another character that did them.

Well, a completion counter could work of course. My point is to determine if one repeatable quest has been completed at least one or has never been completed, to complete every quest at least once, so i don't want to hide quest tracking.

I know that hiding quest tracking will not show any quest that is not relevant to any other collection like achievements or transmogs but I want to treat Quest on itself as something to complete too, nor just a mean for a reward.

For example in the case of daily quest and world quest I want to be able to check if I already have completed every world quest in a zone or currently there is a world quest available today that I have never completed.

The same happens with breadcrumbs, my intentions it to complete every quest, and that include breadcrumbs, so if I complete with my main all possible quest I will miss some breadcrumb, and with other characters I would like to try to complete those missing breadcrumbs. But that should be possible with those changes from that commit, because with a new character the quests completed with by main will be collected and the missing breadcrumbs will be available because the alt has not yet do any quest that invalidate those breadcrumbs.