The reason I left was not so much the outage itself but the fact that I paid for the service, while the free ones were right there available for me (Delicious anyone?). I felt a bit silly paying for the vibe and not something more primary.
EDIT: This was years ago, hopefully it’s more reliable now though I haven’t been following them too closely.
Additionally, Pinboard bought Delicious. The free ones aren't very good about staying in business owing to the fact that they all have costs but no revenue. Thus his claim to eventually eat them all because he has a simple, profitable, business model.