the implication was that a highly motivated and competent software engineer put a lot of effort into making sure that the project meets a reasonable standard of quality and will probably put some effort into maintaining the project

That is entirely an assumption on the part of the reader. Nothing about someone saying "I built this complicated thing!" implies competence, or any desire to maintain it beyond building it.

The problem you're facing is survivorship bias. You can think of lots of examples of where that has happened, and very few where it hasn't, because when the author of the project is incompetent or unmotivated the project doesn't last long enough for you to hear about it twice.

>Nothing about someone saying "I built this complicated thing!" implies competence, or any desire to maintain it beyond building it.

I disagree. The fact that someone has written a substantial amount of non-trivial code does imply a higher level of competence and motivation compared to not having done that.