[betterunix]

"why is garbage collection needed to begin with?"

Well, think about this: what would a declarative language like Prolog look like if you had to manually deallocate memory? At a high enough level of abstraction, it does not make any sense to manually deallocate memory; it may not even make sense to speak about "memory" at all for some abstractions.

"So, what makes garbage collection different than malloc/free, and why is it necessary? I'd love to learn more about that."

It is the same as the difference between having a compiler generate the instruction sequence for setting up stack frames, and writing those instructions yourself in assembly language. As a programmer, your time is probably better spent on higher-level things than how stack frames are being set up. Likewise with allocating and deallocating memory: you will probably be more productive if you spend your time on something else, like the design or logic of your program.

Remember, programming languages exist for programmers, to make us more productive. We are able to do more when we are not being distracted by things like figuring out when it is safe to deallocate memory or ensuring that we do not create memory leaks.