Most web applications aren't built to scale — they're built to ship. And there's a critical difference between the two approaches.
The most common failure point is the database layer. Poorly indexed queries, missing caching strategies, and monolithic data models create bottlenecks that compound over time.
Another frequent issue is tight coupling. When your frontend, backend, and business logic are tangled together, changing one thing breaks three others.
The solution isn't over-engineering from the start. It's making intentional architectural decisions: choosing the right database for your access patterns, implementing proper caching, and designing clear service boundaries.
Scale is not just about handling more users. It's about handling more complexity — more features, more team members, more edge cases — without the system collapsing under its own weight.