[midnightclubbed]

This. Determining when the effort should be applied is the tricky part. Games are still hit driven and get cancelled/re-purposed during development. You can spend a lot of QA engineering time developing systems to test functionality that never ships (case in point would be Fortnight - the original shipped game did not need to be tested against the current 100 player game instances and huge load but they could have spent a bunch of time testing AI systems that are no longer any part of the game).

[blktiger]

I don't disagree that it's important to understand when something is purely a proof of concept vs something that will stick around to evaluate the costs. However, the AI systems are still in Fortnite (and they even used those systems for the Haloween event). The major money making part of Fortnite has been the battle royale mode though. If they open up the main game to be free-to-play similar to the battle royale mode those systems will probably end up being used quite a bit.