Wow, as lifelong web developer, you really got fleeced. This reads like a list of rookie mistakes to be honest, but not just on your side. Agencies should know when they're too big for a client, and they often do. It avoids exactly this kind of dissatisfaction.
And yes, they made money, but the hit to their reputation is usually not worth it if you're their smallest client. I dare say they probably didn't even do it on purpose, they just didn't have the bandwidth to actually care about your project.
I've been looking at Scrum more closely recently, and I think this would have been a good use case for it (with you as a stakeholder). This goes toward your point of doing things one step at a time. Scrum sprints are short and deliver value consistently. Looking back, I wish I'd had to use it stringently while I was still working at startups; I believe we would all have been much better off.
And yes, they made money, but the hit to their reputation is usually not worth it if you're their smallest client. I dare say they probably didn't even do it on purpose, they just didn't have the bandwidth to actually care about your project.
I've been looking at Scrum more closely recently, and I think this would have been a good use case for it (with you as a stakeholder). This goes toward your point of doing things one step at a time. Scrum sprints are short and deliver value consistently. Looking back, I wish I'd had to use it stringently while I was still working at startups; I believe we would all have been much better off.