The purpose of this thread is to discuss the possibility that the completionist feat is a suboptimal feat when facing the hardest content (EE). A prerequisite to understanding the following is a grasp of the concept of constrained optimization. The argument is not that the completionist feat is worse than nothing, but that it is worse than its alternatives.
First, the majority of end-game viable builds that preferentially utilize the completionist feat are very limited. Looking objectively, the completionist feat grants +1 to-hit & damage, a small amount of HP and SP (both level dependendent), +1 to saves, and +1 ability-based DC. The summation of these benefits is considerable, however very few builds can make use of all of these benefits, and they almost always come at a cost of preferential alternatives such as TWF which grant much more DPS than +1 dmg, toughness/mental toughness (themselves arguably suboptimal feats since the decoupling of feats & enhancements), and spell focus feats that offer the same single-school DC benefit. In a world where the majority of characters are feat-starved, the completionist feat offers few advantages for end-game builds. However these builds are also less likely to fair well in EE content, as jack-of-all-trades loses out to specialization at the highest levels of play. One area where the completionist feat retains utility is the DC-caster, as indeed a multi-school caster would prefer completionist over single-school focus feats. With the nerfing of DC casting that occurred with the release of eveningstar-related content and epic gianthold, and the (debatable) high-utility of shiradi casting), DC casting as a playstyle has fallen out of favor, though it is seeing somewhat of a comeback with the elevation of level cap and implementation of yellow augments granting a stacking bonus to DCs.
Furthermore, at the cost of 13 past lives almost any build would benefit from a spread such as 3ftr/3mnk/3pal/3rog or 3sor/3wiz/3fvs/3clr than 1 of each class when considering the benefit of passive heroic past life feats. So from the passive PLF feats standpoint, it is also vastly inferior. Of course if you have a build that does everything, melee/ranged attack, DC casting, skills, and both need for HP & SP, this may be viable.
Basically, it's a mediocre feat that is only truly superior for a small subset of builds for a limited number of classes.
Second, to address a likely misunderstanding of this main point, is the question of whether completionist in itself proves that a player is skilled. This, though unrelated, is also false. Completionist can now be purchased at the cost of roughly 60,000 TP* or under $400 USD via ottos boxes. Each life with a box, if planned optimally, takes roughly 3 hours each without the use of daily dice XP augments, and obviously less if those are taken into account. So from a time perspective you need only invest about 40 hours of time in a select subset of 10 high-yield quests, and $400 of money to attain this feat. The completionist feat has been attained prior to the advent of otto's stone, however the number of players achieving this feat numbers in 10-20 in each server or less**.
In summary, the completionist feat is overrated. Both the actual game meaning of "feat" and the achievement of attaining it. A possible solution is to make the completionist feat auto-granted, such as the free 'passive' heroic past-life feats. This would confer an absolute and unparalleled benefit. I am not arguing that this is what should be done (I don't think it should be done), I'm just saying that in the absence of this change, completionist confers a very minimal advantage, and that players would be better served going 3/3/3/3 instead of 1/1/1/1/1/1/1/1/1/1/1/1/1
*as priced during double bonus points
**i previously stated that there are no triple completionists that didn't use stones, this is incorrect. there are a few, and others that used only the free stone.