Earlier quoted context omitted.
I wonder what you are talking about, Opera did stop and turned into a Chrome clone which brought vivaldi and otter into existence to close the gap it left. I don't get Where the extra click you are talking about is, either click on open in new tab or open in background tab, same number of click. I'm not sure what kind of customization you are asking for, you want to remove the choice of opening in background tab ? Wh…
As an aside, what is a "power user" of a web browser? Almost everyone these days in any kind of office job makes very heavy use of the web for research and apps. People proclaiming themselves as "power users" are just trying to imagine that they have some sort of weird superiority because of their idiosyncratic UI preferences. What a strange thing to be proud of.
It's not a thing to be proud of, or some sort of weird imagined superiority as you put it, it's a fact that in a browser I can do stuff much more efficiently than most of my peers. Of course, this doesn't really matter unless your job revolves around a browser, in which case you could probably shave 10 or more minutes per day (relevant when juggling with tabs a lot, for managers/P.O.s/Scrum masters and such).
Of course, the term "power user" doesn't make sense when talking about barebones browsers (like the old IE), just like it doesn't make sense in Git (where everywhere needs to be a power user, you can't just casually use it like in Hg, without spending lots of time learning it).