To make use of something, you rarely need to understand how it works, just what it can do for you.
To repair something, you do need to understand how it works.
Repairing something you have not repaired before involves making mistakes.
Mistakes often lead to damage, requiring further repairs, which in turn require even deeper understanding.
The more you understand something, the less damage your repairs will do.
But that understanding often comes the hard way.
(Philosophical musings on a badly broken bike)