As a counterexample to that somewhat... I initially tried learning emacs with spacemacs, and the amount of customization in spacemacs’s config made it difficult for me to compare it to much of the emacs documentation out there. Whatever documentation spacemacs had at the time was confusing enough to me that it wasn’t quite enough.
I later ended up starting with a stock config, and I probably could pick up spacemacs now if I wanted to, but at this point I don’t feel the need.
I moved to Spacemacs becaues I wanted to write clojure without maintaining my own Clojure IDE in vim+tmux (this was around 2014, maybe 2015). I was productive in Spacemacs in around 10 minutes. I went from never using Emacs to fixing bugs and writing extensions in Emacs in less than two weeks because Spacemacs pervasively uses which-key to provide discoverability and had vim-style shortcuts I could use for real work (rather than learning a new set of keybindings). The groupings of things into layers makes studying what ecosystem packages provide what functionality much easier than blindly googling "how to do X in emacs" and getting 3000 "unique" (read: half-baked if you're lucky) solutions.
This idea that you should suffer for hours/days/weeks building your init.el from scratch while adapting to terminology, keybindings, and a lack of familiarity with the ecosystem is absolutely insane. If you can use vi, you're better off with Spacemacs.