it's much more likely that a technical student has developed good communication skills than the other way round. in the real world, people are not required to write in depth literary analysis: most people have all the core reading and written communications skills they need after high school.
it's also important to point out that your friend's example is a special case. when looking at the value of a particular degree, it's important to consider the full distribution of outcomes.
the vast majority of people studying humanities degrees do not LOVE the subject. they just choose a certain path after high school that seems interesting. the production of culture has very little to do with what people study at university...
Your friend's career path is not that usual. in practice, most people with this sort of degree will not get the opportunity to make much use of it in the future. None of your listed jobs specifically require a humanities degree, nor is it true that you need to study such a degree to develop good writing skills.
google are a notoriously selective employer, so it's hardly surprising that GPA has limited predictive power within the sample of people who were successful applicants.
it's also important to point out that your friend's example is a special case. when looking at the value of a particular degree, it's important to consider the full distribution of outcomes.