Right but the experience your son had is slightly different than the normal UCAS application and essay since he went through the Common App which I think would flag him as a US student.
The UCAS essay itself is 4000 characters so about 800 words which is slightly longer than the Common App essay. The essay should not mention anything about any particular school one would like.
I am familiar with a student in America who applied to both St. Andrews and Oxford using the UCAS essay and got into both so I’m more familiar with the process via the actual UCAS application than applying to these schools through the Common App. You can’t apply to Oxford through Common App.
I can understand the poster thinking that the American college admissions process feel artificial. I have become familiar with both the UK process and the Ontario process and both just seem more direct.
For the poster, I would say that in the end, it all manages to work out but while you are in the process of applications, it doesn’t feel that way. I think being genuine though tends to come through. Also if the major is important to you, you might want to prioritize that and choose schools based on the major rather than try to fit into a school and hope you will end up in the major you want. That’s what the above student did and ended up with a lot of options including some top American schools without any need to package themselves. Not sure there were any Why Us questions but you certainly would not need to say the school is your favorite when it is not. Perhaps you can approach such a question by writing about what it is about the school that made that school end up on your list.