alt Hacker NewsGood != Successful.
I assume that's why they wrote good and not successful.
It's an average software product with incredible scaling behind it and a lot of elbow grease to keep it chumming along, but it's not great software by the definition of "bugs actually get dealt with"
It's great software in the sense that it makes a shit ton of money though. In the end software that doesn't get used and doesn't make any money but has no bugs is not valuable either.
Not saying that this is the trade off you have to make but if you have a working mode in place that achieves usage and money somewhat consistently i can understand being hesitant about changing it to optimize for less bugs instead.