The one real and visible threat that an early-stage startup faces is dying. The founder's sole mission is to keep it alive. Most startups die because the founders run out of esteem or because they run out of money. Early-stage startups don’t die because engineers chose Python over Java, or because they aren’t on k8s, or because they don’t have a clean architecture. They die because they aren’t fast enough in showing traction.
The one real and visible pitfall that engineers in early-stage startups make is premature optimization. These optimizations won’t make a startup successful. Too many of them will put the startup in the graveyard. The more time that goes on without solving customer problems, the less runway a startup has. The less runway a startup has, the closer the startup is to death.
This does not mean that you should not care about scalable, reliable, and easy-to-understand systems. Best engineers have technical depth and breadth. They are also pragmatic and aware of their biases. When you spend 10 hours a day in the code, it’s common that your view of the world is narrowly focused on the technical side. You must counterattack this bias with a ruthless focus on opportunity cost. This applies to any company stage but especially to early-stage. Your craft won’t live to see tomorrow if your premature optimizations cause a premature death.