Adding that salt is optional. I'm pretty sure the author just added it to the post so people know it exists.

I don't think it's dumb and pointless at all, really. Generally you wouldn't generate a salt yourself if you're using bcrypt however I'm sure there would be cases where it would be needed or even preferred for some reason. I would advocate for flexibility and education rather than rigidity and simplicity. That is to say, rather than make the function useless to those who'd need their own salt I think it's a better idea to allow these options while making sure developers know that they should only be used in certain situations. A function like this isn't bad because it can be misused.