I think the parent's point is that it doesn't need to be like that.
You might be an abstracted adding thingy that adds two numbers to get some other number. But you could also implement a visitor pattern that hooks into the guts of your implementation, allowing me, for example, to inject a logger to record what those numbers were.
Likewise, some ORMs have some abilities to bypass the query engine to hand-write a query, or change the way data types are serialized/deserialized - the key here is basically providing an API to peek under the hood when the user needs to do some stuff at a lower level than the abstraction dictates
You might be an abstracted adding thingy that adds two numbers to get some other number. But you could also implement a visitor pattern that hooks into the guts of your implementation, allowing me, for example, to inject a logger to record what those numbers were.
Likewise, some ORMs have some abilities to bypass the query engine to hand-write a query, or change the way data types are serialized/deserialized - the key here is basically providing an API to peek under the hood when the user needs to do some stuff at a lower level than the abstraction dictates