Most devs either don't or can't bother with proper optimization. It's a problem as old as Unreal Engine 3, at least, I remember Unreal Tournament 3 running butter smooth on relatively weak computers, while other games made with UE3 would be choppy and laggy on the same rigs, despite having less graphical clutter.
I could write a whole essay on whats wrong with UE from a players perspective. But here's the skinny.
Light Bloom, Distance Haze, TAA and Upscaling, no visual clarity, Roboto Font for 90% of all UIs, lower framerate for distant objects, no performance diffrence between highest and lowest graphical settings.
The only good looking and optimized UE games come from Epic themselves, so basically just Fortnite (RIP Paragon). Most of the games released by third parties are Primo Garbagio. They run like ass and look like ass.
But UE is the common denominator for all those problems. I actually don't know any positive examples for UE. Satisfactory, maybe, but it still checks most of the issues. They are just less prevalent because the game itself is good.
There's nothing wrong with it. It just doesn't fit everywhere. There's a thematic difference between Action platformers, Horror and Milsims, yet they all use the same font and UI. Imagine if most games would use Naughty Dogs "Yellow ledges". It would get old very quickly.
I mean, if the world makes it very convenient to use such instruments and call the task finished, this is not okay. I wish at some point we would come to conclusion that we need to optimize the code and software products to reduce CO2 emissions or something, so devs' laziness finally becomes less tolerated.