<p>Many of the grammar conventions taught in English 101, such as not ending sentences with a preposition and using too many contractions are no longer taken seriously, even by professional writers and authors. Did you even read many of the posts in your link? A lot of them say that using contractions doesn’t matter to admissions officers.</p>
<p>I’d still likely to see evidence that UC admissions officers care about this and have rejected applicants for it. I don’t think you can supply that.</p>