I am also a 10+ year GNU Emacs user. I haven't customized it beyond font size and a few settings. I even use the default theme. Other users seem to go crazy and try to make it into a spaceship. Then they claim that it takes a lot of time to customize it. It mainly is very different to operate from all programs and window managers that we are used to these days, and people perceive this as a wrong and try to "fix" it with confusing "starter packs". In reality, its meta features and comprehensive reference documentation make it a closed environment that is very pleasant to navigate.
I can confirm this. Been using emacs for ~7 years now and my config keeps getting smaller and smaller, not bigger.
While I still have my beloved config file, I'm confident that I'd be able to reproduce it within a few minutes from scratch, most of my customizations in there do not affect my workflow anymore.
On one of my machines I'm just using default emacs. Maybe going from all the customizations back to vanilla emacs was part of me "learning emacs" but I think I'd tell my past self that I don't actually have to read up as much as I did and that emacs and vim aren't as scary as many people tried to make me believe.
In the end learning to do the same old things as with other editors doesn't really take more than going through the tutorial, most people will already work as fast or faster by then, before I took the dive into vim and emacs I was very a "mouse and arrow keys" guy when it came to text navigation and editing.
There are of course many things that could be improved when it comes to emacs defaults, I wish the devs were more open to update some of the low hanging fruits.
While making notes about config & tips for various linux software, the bar in my book is actually wether you can live with the defaults and how little tweaking something needs.
It's the exact opposite of sinking costs, and rather focus on "good enough" because you often end up switching or changing stuff soon enough anyways.
So more like how fast can you just go from default install and choose the sanest defaults and not spend time on tweaks / unix pr0n. Install what you need just in time etc.
It makes even more sense when using defaults on several remote systems, kind of like just using vi.
If it works for you, that's great. However, for me it's the analog of "I never configured my shell to have TAB autocompletion." in the old days. If you can live without it, great. But for many, turning it on makes it worth it.