Public-facing example code, be it in a blog post, README or docs/ or even examples/ should be public domain, otherwise it feels like teasing the readers, for their egos, propagandas, laziness or whatever. A ship formed by lots of pieces among these "de minimis" parts from derivates of derivates looks like another ship of Theseus to me, which is more suitable for a custom license. I'd like to give credits to non-trivial example codes. Reading a tutorial full of warnings about licensing sucks. When "the code is the spec" I would refrain from directly looking into the source code for stealing the ideas or algorithms, but well I think guys have "cloned/ported" MIT/BSD code into GPL code and vice versa, even today, and the unaware me is using their code and programs. If I don't want my mind tainted further, I should never crack open their source code. The % doesn't matter in my morality game, although I dislike this game about temptation of free open source code.