No, they're a cool feature but they're for a different purpose.
Symbols allow you to make multiple copies of the exact same object in multiple places. If you alter one of them, you alter all of them. For instance, if you're writing a game book and you want to have one particular shape that means "this takes two actions", you could change that from an arabic 2 to a roman II and it would change in every location where you placed that symbol. (Which is great.)
What I'm looking for is something that, for example, sets the color and border and wrapping of a text box but allows each instance of that box to have different text inside. If I made my sidebars as symbols, every sidebar would have the same text - unless I "detach" it, in which case changes to the original no longer affect it.