Your point is addressed earlier in the article:

It's not about banning new words, killing off long words or promoting completely perfect grammar. Nor is it about letting grammar slip.

A good complement to this article is Orwell's "Politics and the English Language," which talks about how people might use long, complex words (like those in the Words to Avoid list) to seem more important. That's the other side of the "variety" coin. The reality is that a skilled writer can walk that fine line, but most people are better off keeping their word choice simple and direct.