Reasons for Discarding the Core of the Onion When Chopping? A cook I know always discards the core of the onion when chopping it.  Is there any reason for this?  In professional demonstrations and cooking classes, I've never seen it done.  From observation, it does seem to make chopping or mincing the way I've always been taught a bit easier, as the core can be awkwardly shaped, but other than that is there anything besides personal preference to it?
There is one reason I might do this. If the core is green, that is starting to form a sprout. I cut that out as it can be bitter. Otherwise I don't know why one would do that.