I too did long ago buzz wrongly - big mistake
Since then I have buzzed correctly, if I may use that odd distinction.
In my opinion there is wrong buzzing and there is correct buzzing. I need to clarify this apparently odd and bizarre statement.
Wrong buzzing is for me the creation of a buzz between the lips that can start a standing wave in an instrument and this creates an annoying raucous noise.
Correct buzzing is not something we create in order to make a standing wave appear. It is instead the result of the lips naturally vibrating together when air is passed between them.
The distinction is critical and profound, and you are absolutely right when you say "the sound emanating from a vibrating column within the horn which, in turn, causes the lips to vibrate", that is the best description I have heard for what is really happening.
Because the lips vibrate as a result of correct technique it is way too tempting to decide that making the lips vibrate is the goal and will result in correct technique, and many have made that fundamental mistake.
As in a case of placing the cart before the horse, no progress can be made when you make the buzz the goal.
I think it is the US Army Field Band who teach correct sound creation for beginners by this method - "place a tiny straw between the lips and slip a mouthpiece along it to rest on the lips, then blow into the straw steadily, and then while blowing through the straw pull the straw out and a beautiful and steady tone will then appear.
They do not teach to buzz they teach instead correct embouchure chops and mouthpiece placement coupled with a tiny and relaxed opening between the lips.
This is the lips buzzing (or vibrating) correctly as a result of correct technique and it is not buzzing in the hopes of correct technique emerging.
The buzz exists but it is a consequence of and is a result of how we play and it should never be considered what we must do in order to play.
There is an additional concern. If we play into an instrument, we can hear and the audience can hear poor tones and beautiful tones. If we just buzz our lips or into a mouthpiece it is far more difficult to hear the difference between the two and work on improving our tone.
Our task as musicians is to make the tones we produce the most beautiful humanly possible and we do this by making improvements to embouchure chops air support etc, and these changes will modify the way the lips buzz together.
What we must aspire to then is a modified buzz developed by improvements to the way we play. The buzz will take care of itself if we take care of the tone.