Any game engine evolves towards serious complexity as time goes on. The question is, do you want to waste time building systems that a million man hours have go

Any game engine evolves towards serious complexity as time goes on. The question is, do you want to waste time building systems that a million man hours have gone into to make them resilient across a thousand different permutations of hardware? Or do you want to ship your game? I've built a non-trivial engine active from around 2010 to 2015 that targeted all iOS and Android devices. Our test fleet of devices was enormous because we'd run into silly issues that were always device specific. My favorite, one particular phone with one particular driver version for the GPU did not correctly implement the ES 2.0 standard for constant defined variables. It caused our games to crash, and because of the scale of mobile this affected hundreds of thousands of users. At this point you could not pay me to build an engine, because for anything that isn't a toy you end up having to solve these problems yourself. Treating Unity as a rendering engine and asset loading system is not immediately "easy", but it's a very far cry from "hard". Dismissing it or other options simply because of unfamiliarity or a shallow distaste for OOP is ignorant at best and actively misleading otherwise.