I'm not sure why this intuition is so strong, I had it myself before learning this stuff in my early 20s on shipping projects (both existing, and from scratch) and at the end of that I was still in my early 20s.

Despite this intuition it's all actually very learnable and my experience is that using a parser generator makes no sense in a professional context and very little sense in a hobby/toy project context.

With any luck that will happen to you sooner or later.

Better to have it happen knowing you've mastered some subject.

Why do you think people are writing toy programming languages?

It's a learning exercise. Sure, if you want to learn to use yacc, or whatever, use yacc. I don't think time efficiency is a useful metric when the overwhelming majority of people is this space aren't doing it for their job, or even because they 'need' to create a new language.

Ultimately you could just use python, it'll be faster and more fully featured.