Because people have a natural tendency to omit them at the end of the line.
Fascinating. I've never heard of, nor observed, such a tendency. Might you provide references to a few peer-reviewed studies on the topic? I don't necessarily need URLs or DOIs (although those would be most convenient) - bibliographic citations, or even just the titles, should be sufficient, since I have access to a good academic publication search system.
Offhand, the only potentially-related publication I can locate is "The Case of the Disappearing Semicolon: Expressive-Assertivism and the Embedding Problem" (Philosophia. Dec2018, Vol. 46 Issue 4), but that's a paper on meta-ethics, not programming.