Is it still necessary to keep copy, paste and cut under Edit?

Right click -> Copy / Paste / Cut and Ctrl + C, Ctrl + V has been around for awhile now. Most applications has this, yet they still add Copy / Paste / Cut under the Edit menu. Even in software used mostly by power users.

Why is it still necessary to add them under an Edit menu? Will users have difficulty finding them if it's only in the right click menu?