it's more of compression. fastest way to get 10 yrs of backend sense in like 3 weekends is build fake OS scheduler or just kv store with fs persistence. and the shortcuts your brain takes after that, scary fast. you just start seeing stuff everywhere. like oh this LRU cache is just dumb DLL with hashmap. or this parser is just recursive descent with some peek-ahead logic stapled on. and then you can't unsee it. you start breaking down every abstraction you touch. even prod libs look like toys.

also lol toy projects expose your defaults hard. how you name vars when there's no PR. how you layout dirs when no one's looking. do you even test stuff or just printf until it works. do you log or do you trace or just guess.