I was playing Zimbabwe with defensive ideas (+1 attrition for enemies from each) and Delhi was throwing 50k stacks on my forts in south India and tanking the attrition like it was nothing. They were literally jungle provinces. Delhi shouldn’t be able to just ignore attrition like that.
This is literally a videogame, not real life.
Hyperbole aside, there are reasons for attrition to be uncapped. That was the case in the past and lead to terrible results where AI would bleed all of its manpower against a Human player all the while players were able to stop this from happening to them with ease. While not a good solution, capping attrition does help the AI and it sure as hell needs all the help it can get.
Shiny bells and whistles like ideas and monuments aren't a substitute for good game design. If the AI can't handle something as fundamental to the game as attrition, Paradox should fix the AI.
At this point the game is too far gone for us to hope for any meaningful improvement to the AI. Think about it for a moment. EU 4 was built upon EU 3 so the team that worked on 3 was, for the most part, carried over to 4. EU 3 has about 15 years and EU 4 9. There hasn't been anyone at the team that truly knows how all this stuff works for a long time and the game has had so many changes over the years that trying to steer the boat into another direction only leads towards disaster (see everything that happened to the AI since Emperor).
Having said all of that, the last public patch does give me hope for the future but I still think that any meaningful changes to the AI will only truly he possible in EU 5 when they get a dedicated AI guy to write a new AI from the ground up.