With a lack of background knowledge, it is not uncommon for a simplified understanding to be taken as a sound basis for everyday living. I mean, it seems to work, doesn't it?
But the fact is that fuses are fickle beasts. While you can rely on them acting, you can't be particularly certain as to when they will act.
This characteristic is demonstrated in household power protection in Australia - well, NSW at least. Our standard power point circuits that were protected by 15A wire fuses could have those fuses replaced by 20A circuit breakers - with absolutely no wiring rework. The reason being that the point where the wire fuses would blow was so varied that they added a safety margin in the gauge of the wiring. However, with circuit breakers, the breaking current was much more predictable, so they allowed them to be higher rated, using up some of that safety margin - but without impacting safety.