You cannot really believe that a few posts on HN, whether they are positive or negative, really are a good indicator of Coinbase's reputation, can you? Anyone can post anything and the more negative it looks the more people upvote it. Upvotes do not correlate to truth or accuracy.

For example if I were to post that I have used Coinbase multiple times with no problems I wouldn't expect to see a single upvote. It isn't news.