Sinnerbaits vs spinners.......apples and oranges. Bent arm spinnerbaits, includinging the safety pin style we are so focused on have 2 different wire configurations used as the tie off point. One is an "R" style bend (such as the Kahara) and require a direct tie off lest the snap continually slide up the arm and foul.

The other is closed and either option (snap or direct tie) is used. There are some advantages to a snap system as the freedom of the loop permit an instant alignment of the spinner itself. Picture, if you will, a direct tie off......any curve in the line will need be absorbed before your lure runs true.

For example, make a long high cast on a windy day and a large arc will be formed in your line. On a direct tie there is little or no freedom and the lure must follow where the knot leads. This can be particularly debilitating to true "spinners" which might not kick on at all.

Having said all that  ;) I am still a fan of a direct tie on spinnerbaits but am careful to avoid large arcs in my line.