True. But ... those are the settings that Google recommends and supports. I don't know how their system is designed but I would caution you to use the service as specified.

Deleting:

Do NOT save deleted messages on the server. Messages that are deleted from an IMAP folder (except for those in [Gmail]/Spam or [Gmail]/Trash) only have that label removed and still exist in All Mail. Hence, your client doesn't need to store an extra copy of a deleted message.
Do NOT save deleted messages to your [Gmail]/Trash folder because this will delete a message in all folders.
Do NOT save deleted messages to your [Gmail]/All Mail folder as some clients will try to empty this folder and ultimately fail. This can lead to delayed mail access or excessive battery consumption on a mobile device.