You're missing that a default vanilla Emacs experience is pretty shitty. Besides, it's not like you're sacrificing any customizability with Doom/Prelude/Spacemacs, you're just getting a better starting point.

You can consider doom emacs a 'mod' that make it easier to manage your customized emacs config.

If anything I found doom to make it easier to stay close to the 'intended' way to customize emacs, since it heavily encourages you to use 'use-package' and 'general.el' to manage your extensions, and gives you good startup performance if you use them as intended (allowing the lazy-loading to do its work).

Although it's possible I was simply more familiar with the 'right' way to do it when I moved to Doom from Spacemacs. Either way I got the impression it felt quite close to the way to manipulate 'native' emacs (but with a lot of sensible defaults that I couldn't be bothered to figure out myself).

I went with the ‘take vanilla and adjust’ route to learn proper Emacs config-ing. Turns out, you pretty much need to implement a bunch of features on top of the 90s Emacs to get a reasonable modern editor, and there isn't a system for config snippets that are smaller than a minor mode (aside from copy-pasting from StackOverflow). I've been meaning to try Doom for some time because it seems to be an answer to just that problem.

Maybe many users don't need a very specific configuration, and a great community made configuration is good enough :)

I use Spacemacs which is also a community made emacs configuration and it's great. The fact that I could have made the customization myself does not make this configuration any worse.

Projects like Doom Emacs and Spacemacs are frameworks. They contain lots of well-made, battle-tested code. They are extensible, too: they usually provide clear points for user extensions and customizations.

I think what you're missing is that Emacs might be a good fit for things other than "the main idea of Emacs" (whatever that is)