Sure, but typically it's deliberate on the part of the author.

Right. You should know the rules so you know when to break them. Stephen King hits on this point well in "On Writing." That book is a great read and takes a very non-parochial approach to writing.

If you are Joyce you can get away with changing the rules - but nobody is going to read you anyway.

Similarly if you are Knuth you can talk about literate programming replacing C but nobody is going to hire you to do embedded development