It’s a commonplace that the people (or bots) selecting answers for the Digest are not the same people (or bots) that moderate answers. Answers that appear in the Digest are routinely collapsed after the fact, because the two tasks are undertaken by two separate parties.
Of course, answers get collapsed if they are reported by someone, and moderators agree with the report assessment: Quora is not resourced to collapse all answers proactively. The more visible an answer, the more likely it will be reported by someone, because someone will notice it and not like it.
And answers that appear on Digest are more visible than others.