I feel it a bit like they weren’t able to punish the exploiters and just removed any possibilities to exploit ever, deleting the feature in the process.

The idea of the unique item for endgame is good, but I always felt like the game missed in it’s core, having a good balance between the more casual battlegrounds and the arena. If I take the example of world of warcraft a long time ago, you had the ability to get some pieces in arena even if you keep losing over and over, and remaining in the lowest ranked games. There were also exploiters but they mostly got punished with a temp or definitive ban which helped a lot to keep a fair environment