So in early development, GGG had designed an infinite dungeon then decided to scrap the idea in favor of maps. More than one reason factored into this, however, the main reason is pretty simple. It kills build diversity along with making player expectation around character performance a huge problem. So why it kills build diversity is pretty straight forward, you will have one goal, maximize loot / EXP for player input. This becomes a min/max race and very quickly whare ONE build begins to rule them all. Now some of you may think that this is how POE functions already, and your not wrong . However what an infinite dungeon does is makes this problem much worst and the sole direction for builds in the game. The second problem is the player expectation. What happens when your "fun" build can't get anywhere in this dungeon ? You will feel as if you have failed, since it will also be stumped on a map tier and poor at farming bosses. This leads back to the same problem, players will gravitate towards the one build to rule them all. This is what happens in the greater rift community in diablo 3, you are limited to how well you do on the leader board based on what build you are running THEN how optimized the build is compared to other identical builds. In PoE, however, another major problem will be that unlike diablo 3 whare you can farm any gear you want relatively easy, in this game you will also be gated off from better gear / more EXP AND PoE currency. Also, players will not want to push themself as you might think they would as the risk/reward system will punish them, so they will fall back on speed farm builds to farm the easy part of the dungeon. Not enough information about delves and how they compare with end game maps in terms of exp/loot per hour. It might not be very lucrative and be more of an ego swinging contest more than anything. Map wher the solution to this problem and a great solution it was, however from constant crying on reddit and game forum about map pool sustain, and junkey like players deciding to farm low level content. The map system has morphed into a shitty form of greater rifts already, this dungeon is just a formality at this point and IMO a sigh that the original vision of PoE is dead and never coming back. This is why a LEAGUE is a great place to try it out. If it actually kills build diversity, then it doesn't get added to the main game. OR, they nerf the 1-3 builds that are obviously miles ahead (because now we have actual data that shows what is ahead), Buff some under performers, and now we have 12+ builds that can all go deep into the mines.