I experienced this with Mailbox when they were launching late last year. It was slightly annoying having to be on the waitlist, but as a small team, scaling an app or service can be and usually is tough. Anticipating the demand is hard to predict or even model. You just don’t know and if you’re overloaded, it ruins the user experience. Unfortunately the customer is always right and they will complain even if it really isn’t your fault. As someone looking to go into development or at the very least understands the developers’ perspective on this issue, I have to side with them. Mailbox eventually scrapped their wait list because Dropbox bought and supported them with their huge infrastructure, which was already in place.