Not weird at all if people don't strictly follow a standard.

The world of programming, just like the real world, has a lot of misguided doctrines that looked really good on paper, but not on application.

For example:

    "_links": {
      ....
      "cancel": { "href": "/orders/123/cancel", "method": "POST" }
    }

Why "POST"?

And what POST do you send? A bare POST with no data, or with parameters in it's body?

What if you also want to GET the status of cancellation? Change the type of `method` to an array so you can `"method": ["POST", "GET"]`?

What if you want to cancel the cancellation? Do you do `POST /orders/123/cancel/cancel HTTP/...`, or `DELETE /orders/123/cancel HTTP/...`?

So, people adopt, making an originally very pure and "based" standard into something they can actually use. After all, all of those things are meant to be productive, rather than ideological.