Yes, in fact, this is why people who do that are looked down upon.

They are in fact committing fraud if they do not attribute the code in their commit properly, because by committing it they’re claiming to have rights by virtue of authorship that they do not have. (Namely, the right to contribute that code to the project,.) They may also be committing copyright infringement, depending on the copyright and license status of some code they found via Google or Stack Overflow.

It’s always fascinating to me to see how many people on Hacker News have such extremely poor understanding of how intellectual property actually works, and how misrepresenting themselves or their work can actually have consequences.