Ah, now we've gotten to the very nut of it: you don't think that secretaries are essential. Never mind that the sort of folks who employ them seem to think that they are: you, who aren't in their position, don't, and that's enough.

I'm reminded of pg's famous essay on the Blub Paradox. Programmers who use a semi-powerful language can see that others are less powerful than theirs, but can't see that more powerful languages offer anything much. Likewise, folks at one level of society can easily see that it makes sense to hire others to grow their food and make their clothes, but can't see that it makes sense for others at other levels to hire people to manage their schedules and correspondence.

A good secretary is a lever for a decision-maker.

I'm sorry you think the many people employed as secretaries should lose their jobs because you think their job is "unessential", but that attitude is patronizing and demeaning to the people who hold those positions. This world isn't about you, and you you have neither the right nor the authority to tell them how to live their lives.