I dislike it particularly because of the implication of stupidity: "I believe only stupid people won't know this, but I'm going to tell you anyway".

In general it's poor form to assume readers know anything - consider (for example) a future lay-reader who is trying to find out this information.

Because it's a tired, overabused cliche.

But we are not grading an English essay are we? The content of the article was quite good for a "normal" non-tech person.

I don't think the content of the article was particularly good.

The advice on how to protect yourself from being spied on is essentially:

"stop using the internet; or use HTTPS - which is probably compromised anyway; or encrypt - which is probably compromised anyway; or use a VPN - which I will say next to nothing about"

It's just a rehash of points and opinions already better expressed elsewhere.