I am following the online course to all grain brewing on "craft beer and brewing" and in the lautering sectiong they explain to collect the first runnings and to put them back on top of the grain bed. This is done to avoid leaving particulates in the wort. They suggest to collect something like 4 cups and do the process 5 times.
Seems like a really inefficient way to simply filter out particles. Why not simply use a strainer for the first gallon of wort?
Am I missing something here (other than tradition of course!)