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.