Looking up the requirements for the lower ranks in the current Handbook, however, I find that the Sheet Bend is no longer required for advancement. It's still shown in the section on knots and lashings, but you don't have to learn it. I am flabbergasted at this. One is far more likely to need to tie a Sheet Bend than, say, a Bowline. For that matter, how does it make things easier to remove a knot from the required list? There are still multiple knots and lashings to be learned.
And how long has this been going on? When did the Sheet Bend slip beneath the waves? It's an outrage, I tell you.