I've seen many home made router table fences where the sacrificial plates have a 45 degree angle at their vertical edge at the table router side. Examples are here, here, here, here, here, here, and here.
Why are the edges of these parts cut in a 45 degree? It is an excess task during the process, especially if one does not have a table saw at his disposal and I can see only the very marginal benefit of having the guiding fence a few millimeter closer to the router in the case of a very shallow rabbet for very short working pieces. In all other cases a "normal" 90 degree cut would result in the same guiding function.
Since so many people do this, there has to be some reason behind it. What could it be?