I totally agree with "you can't just replace availability with pagerduty" if you're dealing with stuff like pacemakers. But that's not what most startups do. I

I totally agree with "you can't just replace availability with pagerduty" if you're dealing with stuff like pacemakers. But that's not what most startups do. I believe that too many engineers worry about "what if a million users sign up tomorrow" and plan a system that will handle that (which also happens to be fun and tickles all the right places), which takes a lot of time and money and manpower instead of building something that works reasonably well and worrying about building the "right" solution when they're beginning to actually grow rapidly. I'd much rather hear "our servers can't handle the load, there are too many users signing up" than "when we're done here in six months, our system will be able to handle any load you throw at it". I wouldn't say that it's a no-go (there absolutely are situations where it makes sense), but it often looks like premature optimization.