I'm not gonna watch the whole video, so apologies if this is addressed in the video.
It's not necessarily a problem of the engine. Sure, there are bugs, compatibility problems, regression, etc that will happen from time to time, setting back development milestones or simply just break existing games until they are patched.
But, the cause here is the people using the tools: AAA-studios have laid off so much staff that experts regarding UE(5) aren't involved anymore. Plus, QA, and by extension optimization, has been hit hard too.
So you got developers who don't fully know how to use the engine to its fullest, and a gutted QA department that won't be able to get all the issues reported, tested and prioritized anymore.
I used to work in game development as a Designer, Programmer and even QA. Definitely missed the industry at times but seeing the state it’s in now, I’m glad I left. I’m fortunate to have experienced it around the time of PS3’s launch, it all went downhill after that it seems.
I'll take good art direction over realistic graphics any day of the week. I just replayed Bioshock infinite and for all I care it looks far better than your average AAA of choice.