Games and other specific applications call for such unidirectional data flow with such massive amounts of "independent" entities. It isn't that it'll catch on or not outside the gaming industry, it is more of a unique solution to a typical gaming problem.
So their are apps that do use similar or ECSs architecture under the hood, it is just more problem related not a solve everything solution.
right, I guess what I mean is that in the past you would pick an architecture based on your data structure/flow, performance requirements, things like that. Now there is a new metric: how LLM-friendly it is. Probably it won't be a huge factor, since a properly structured REST server would also be friendly enough, and LLMs are getting better. Still interesting to consider though, IMO.
So their are apps that do use similar or ECSs architecture under the hood, it is just more problem related not a solve everything solution.