A typo. Should read "without it." Again, the data layer on a BD is very close to the surface. So, light scratches could potentially ruin the disc. Thus, they use a hard-coating to help prevent scratching. Originally, they were in some kind of casing, but that would have increased the cost to produce them.
Absolutely correct, although I have seen some interesting things happen due to the close data layer. I have seen the BR laser imprint fingerprints into the data layer, permanently corrupting the disc.
Granted this was only with BR burners that I've seen this occur with, it still cost my old company quite a few discs. Now I'm paranoid in general, constantly making sure there's never dust/fingerprints on my discs.