[Melatonic]

UE5 can make a great and efficient game actually - its more about how you use it. And because its huge and popular and accessible there are a ton of developers using it very inefficiently.

That can be true for any commodity software though. Designing something inhouse means you inherently will have engineers and experts with better low level understanding. It doesnt mean it will be better (could even be much worse) but theres a tradeoff there.

[cubefox]

Yes. You basically still need a few engine programmers to use UE5 efficiently, even if it's not your own engine. UE5 seems to be user friendly enough that most of the game development can be carried out just by artists and game designers, but without engine programmers performance optimization will be poor.

[gambiting]

The core part of UE5 that people seem to forget is that it's FREE. During development you pay Epic exactly 0 dollars and even after launch you need to make very decent sales figures to actually pay anything at all.

So a lot of studios think oh, the engine is already finished, we just need artists and designers to use it, all the heavy lifting has already been done. And while yes, you can make a game that way, the results will be sub optimal. But then again, free is infinitely cheaper than having an engine team maintaing your own engine or any custom elements of UE.