Yeah, unfortunately doom isn’t designed to be beginner friendly. I’m personally in two minds about customize. It is quite clunky and I think it’s too easy to have your customisations overwritten by customise or something else or to have them overwritten in confusing ways. But it also gives a non-lisp interface to a lot of customisation (manually setting up the data structures can be a big pain to get right without it).
I'd also say it's a good choice for beginners. Providing one way to configure things and explaining that reasonably well in tutorials and docs is fine.
The only downside of Doom Emacs for a beginner like me is the non-standard package manager: Just following some packages docs for configuring isn't enough, it's also required to figure out when to execute that config code.
It's easier this way for a beginner. Things are consistent; You put `(setq foo bar)` in your config. It's very intuitive. (I have also lost some settings to customize's bugs in Spacemacs.)