A nitpick but arguably an important one for your point - this article argues that the efficiency cores aren’t for “browsing the web / watching YouTube / checking emails” but for non-interactive tasks like Spotlight indexing (based on GCD scheduling priority).
<personal rant>
I'd swear that Spotlight indexing would prefer a freaking supercomputer when it runs.
My whole system just starts to feel sluggish, especially if I just moved a bunch (say 1-5GB) of files onto my system and not it wants to index them.
</rant>