What? I mean, it's a bit brutal in the phrasing, but the honest truth is that all businesses should strive to design their orgs so that people are replaceable.

That's good for the employee too. In the strictest sense, if you can't be replaced in an org, that means you can't grow, change or shift to new positions.

I've lived this. Typically, when I submit my resignation, immediately the responsibilities and tasks of my current position get handed off to others or dropped, because, well the business is replacing me.