An example: Page numbers are considered obvious nowadays, but they are still in a lot of published works.

Can you name a recent published work wherein the subject is page numbering?

Does this matter?

Any book will serve as published prior art against a patent on page numbering. It does not have to be the main subject.

My point is that there are many small problems which we solve as engineers every day that are too trivial to publish in a paper.

It is all well and good until some moron (genius?) comes along and patents these simple ideas.

Just push your source out in the open. Then you will have published every small idea that's in your code.

Publishing your stuff in an academic paper is not necessary for these purposes.