They've adjusted accuracy requirements.

Only SE has the numbers so take this with a grain of salt, but my perception is that the minimum accuracy from bosses has been nerfed, meaning if T13 had for example an accuracy cap of 515, if you had 400 you would literally miss 50% of the times (making DPS without accuracy almost unviable). It seems this is no longer the case, because despite people claiming that the accuracy of Ravana is well over 500 too, I don't seem to miss much even with 354 accuracy, so I suspect the minimum % to hit a boss has been upped (if I had to take a wild guess, I'd say around 70%, so you still hit pretty consistently even with 0 accuracy).