[enra]

At Airbnb, we also started building the library with symbols but noticed that it didn't work, at least before Sketch 3.5 or something.

In our case, we want that people can change the symbol sizes (eg. you need to fit in more content in to a header). If you need resize or accidentally resize something, Sketch would automatically resize every instance of that symbol. That would kill your sketch for few moments and probably mess up your file permantently (sometimes you couldn't undo the damage you had done.). So we ended up putting the components in Layer Groups, and let people copy and paste them.

Newer Sketch symbol support have gotten better, but I'm still hesitant to change to it, since it seems something they haven't nailed down yet.