Use of FROM keyword on DELETE statement
Here is one case where it would be hard to write it without:

DELETE /* FROM */ t1    -- this FROM is optional
  FROM dbo.t1           -- this FROM is mandatory
  INNER JOIN dbo.t2 AS t2
  ON t1.key = t2.key
  WHERE t2.key IN (1,2,3);


Or:

DELETE /* FROM */ t1    -- this FROM is optional
  FROM dbo.t1           -- this FROM is mandatory
  WHERE EXISTS
  (
    SELECT 1 FROM dbo.t2
    WHERE key IN (1,2,3)
    AND key = t1.key
  );


The FROM in the initial spot (e.g. DELETE **FROM** t1 FROM dbo.t1 ...) is optional, just as Books Online says. Why do you think it ever should be mandatory? Borrowing from Thomas' answer, which he gracefully deleted, the following are identical:

DELETE Sales.SalesOrderDetail WHERE SalesOrderID = -1;

DELETE FROM Sales.SalesOrderDetail WHERE SalesOrderID = -1;


This is similar to INSERT - the following are absolutely 100% equivalent, and you don't ever have to write INTO:

INSERT dbo.t1(key) VALUES(1),(2),(3);

INSERT INTO dbo.t1(key) VALUES(1),(2),(3);