This is not true. The code can be flawless, slightly buggy, maintennable with some effort, hardly maintennable or unfixable. And then there are personal preferences and opinions about what is good code.
The algorithm can be slow, slightly faster, fast.
The intro into framework can be in the middle too.
But within context of a tutorial, anything less than flawless is not worthy of inclusion (making it binary in this case). IMO, any content aimed for beginners should be flawless.
Beyond introductory material, it's a trade off of complexity and time as it's hard to compress the factors needed to demonstrate anything technical.
The algorithm can be slow, slightly faster, fast.
The intro into framework can be in the middle too.