To be far - in order to apply to Stanford you need to write 11 supplements and pay a $90 fee, as @sbballer pointed out. And while I received lots of advertisements from various colleges after taking the SATs I don’t recall Stanford ever sending one. It seems they’re pretty genuine about not inflating applicants.
I like the Common App. It doesn’t make it less work (I spent more time on Stanford’s app than I did on MIT’s app), it just makes it easier to organize requirements and submit things in one place. (@teddymittens2)