MongoDB is useful when a product needs flexible document-oriented storage rather than strict relational modeling from day one. It can be a strong fit for evolving data structures, content-heavy workflows, event-like payloads, and applications where shape flexibility is part of the product reality.
I use MongoDB selectively, not by default. The value is highest when a system genuinely benefits from looser schema design and when the team understands the tradeoffs between flexibility, consistency, and query structure.
In the right scenario, MongoDB helps reduce friction for products that move quickly and need to store data that changes shape over time. In the wrong scenario, it can introduce unnecessary looseness. That is why I treat it as a practical tool for specific product patterns rather than a universal database answer.
Used carefully, MongoDB can support clean, adaptable backends. The important part is aligning the storage model with the product's real data behavior instead of choosing technology based on trend alone.