Yes, but with a book, you usually have an editor look it over and have someone proofread for you.
Yes, before it goes to the public, at which point it's too late.
I don't think it's a problem, really. Be your own editor before the public gets it.
Besides, when a post gets edited, it gets bumped back to the top of the Active pages, making it more visible, thus making it advantageous for spammers. If this is something that they feel should be corrected, they would just need to remove that "bump" function.