As a pedant I take a backseat to no man, but... The definition of a lanyard is not as rigid as you suggest. While I would agree that the loop is the most commonly cited elemental characteristic, it's less than a consensus. Given the wide acceptance of the term among knife people to encompass "fobs," I wouldn't be so quick to judge it as wrong.
I have to disagree. The term is used incorrectly with any "lanyard" used for a knife, sword or sidearm, unless it allows you to secure the item against loss. A "fob" is properly used as an aid in gaining access to something. A pocket watch fob would be a common and simple example. I guess you could consider a watch chain a type of lanyard if it secures the watch to your person. However, I have never seen or heard the term lanyard used with a pocket watch. Maybe you have.
Just because something is widely accepted, does not mean it is correct. For example, the term "Crescent wrench" is common place but, the proper term is "Adjustable wrench." Crescent is just a brand name.
My guess is that the term "lanyard" is so common with knife owners is because of marketing. Knives are advertised as having a "lanyard ring" or "lanyard hole".
Sounds exciting, right? You have such an exciting and active lifestyle that you need a lanyard ring! "Fob ring" or "fob hole" just don't sound as high speed so I can see why they would be avoided.
Just my 2 cents.
I am sure this has already been posted but it does support my opinion:
From Wikipedia, the free encyclopedia
A lanyard is a cord or strap worn around the neck, shoulder, or wrist to carry such items as keys or identification cards.[1] In the military, lanyards were used to fire an artillery piece or arm the fuze mechanism on an air-dropped bomb by pulling out a cotter pin (thereby starting the arming delay) when it leaves the aircraft.[2] Aboard a ship, it may refer to a piece of rigging used to secure or lower objects.[1]