I'm not saying performing well in these kinds of tests makes a person one-dimensional or lacking in other areas, it's just that, like you said, a lot of the skills can be spoon-fed - I remember reading the list of top performers in the BMO when I got my result back and it was pretty much a who's who of top grammar and public schools. Clearly there's no-one who can do well in tests like the BMO with just coaching as genuine talent is needed too, but to have so many high performers from the BMO does give preference to highly coached public/grammar school students. As a personal choice I'd rather be among other students who have strong mathematical potential, but who have not as yet been trained rigorously - I don't want to feel like I'm behind the rest of the field before my degree even starts.