Lots of don'ts without clear explanation why, I think some of them are status Quo rather than properly reasoned approaches. I don't see why it's bad to use full-screen modals in some cases. First, It may very much depend on the type of content and size of the screen, and second stretching a modal full-screen helps with reducing distractions around modal content.
Another thing that bothers me are nested modals. Drawers are technically modals too, and modals can be used in a way when nesting them would help to organize complex information in a hierarchical way.