RE Engine: Monster Hunter, REMakes, DMC. All run beautifully
Idtech: Doom 2016 and Doom Eternal are super optimised on low end hardware
Then you have Unreal Engine 5 which needs top end hardware to run (Remnant 2, Lords of Fallen) and
Gamebryo/Creation which still has bugs from Morrowind in Starfield.
Not sure if related but City Skylines 2 needs several times $$ investment for slight improvements over Cities 1 on Unity
Now a splash screen either makes me smile or cringe. Just wished everything ran RE engine
Re-using engines has been around for basically as long as game development has existed. This idea of some mythical age when game development was more “pure” is a fantasy. What has changed is that expectations on AAA titles has grown to the point where it’s extremely difficult to roll your own engine if you are committed to many, many years of work.
Not to mention, it certainly doesn’t guarantee that the engine performs well. Look at Starfield or Baldur’s Gate 3. Both have noticeable issues with performance, and both are built on in-house engines by their respective studios.