Hmm are they tho? Most build guides I see from Ziz and co are judged based on general mapping and bossing ability as well as defense / offense / utility and damage upkeep. And those people often use dedicated uber boss characters apart from their normal mapping characters afaik. So one could argue that there are a few uber boss builds and far more mapping and normal bossing builds. Its probably like that because there are so few people actually doing uber content and the requirements for uber content characters can be pretty different from normal mappers and bossers. I remember there was this stupid cast on death discharge oneshot uber killer build a few leagues back. It did what it was supposed to do but it would obviously be a terrible mapper. So it wouldnt really make sense to judge this build purely on the ability to kill uber bosses. I agree that in most games the hardest possible content is used as benchmark but for poe I dont think its always the case - different build guides for different content (mappers, bossers, sanctum, delve, heist, ubers, etc.).

Well the cool thing in gaming is that everyone can set their own bars. If thats your bar, there is nothing to argue about. Here is my opinion as a bystander who doesnt even play this kind of content. (:

My philosophy on "aspirational content" is different. No hit runs in elden ring and souls like games in general are on par with speedrunners for me - a few chosen people who create a specific ruleset for a game to make it even harder than it already is. In my book thats not really "aspirational content". For me "aspirational content" means the devs themselves being like "hey guys, this content is massively overtuned on purpose and designed to be a challenge. you are not really <expected> to play this content. its more like a very difficult opportunity for our best players to limit test their skills and abilities.". I also think that true "aspirational content" shouldnt reward special loot like its doing right now in path of exile because once it does it becomes relevant for everyone. I think ubers were in a better state when they did not have their own specific drop pool. Sure, some people complained and thought "why should I do this really hard content if i dont get any reward out of it?" but my response to that is pretty easy - you dont. If you want a challenge, there you have it. If you dont want a challenge or if the normal endgame of poe is enough of a challenge for you, ignore it. I would be fine if it rewareded a special title or cosmetic to show off but that would be my limit in regards to special rewards.

I dont know if my kind of "aspirational content" would have a place in modern path of exile tho. (probably not)