The first wall you hit is build complexity - and the fact you can have basically non-functional builds by the time you reach maps.
You battle to overcome that one, maybe use some guides, and then you find yourself in front of the taller wall: taking a character from 'okay' to 'powerful' is often a question of currency that most players can't answer. That ED/C build gets you to maps on basically nothing, but the ceiling is painful as hell to whack your head against for tens of hours.
Finally, you somehow scrounge together enough bread to complete a build and encounter the tallest wall of all: build min-maxing, where every tiny upgrade (sometimes as low as 0.5%) is numerous Exalts of investment.
At the end of it all, you have a character that can beat all content.
To do it differently, however, you need to be playing a different game. For some, POE is an investment/economics simulator, where they sit in their hideout crafting items to sell or scouring the trade sites for flip opportunities. Lots of money to be made, but you're no longer playing the same game. For a lot of those people, currency stacking is the beginning, middle and end of their POE experience. Path of Math, for example, is a guy who makes currency strategy/high end crafting videos. All he does with his time is evaluate how much money he's squeezing out of every map/league mechanic. He buys a build that can clear that shit as quickly as possible, then shows other people how the top 0.1% of the player base (if that) generate thousands upon thousands of Exalts.