Buzzing can be good - or it can be bad - it just depends upon the player.
Myself - I have a "manufactured" embouchure. ie I have been playing 38 years and over that time I have developed an embouchure that works. It isn't a "natural" embouchure.
If I was to start learning again........I would start by free lip buzzing, then MP buzzing - then try it on the instrument. It is tempting to do that even now for me - but my teacher tells me that it would take at least two years to start again with a "natural" embouchure, to get where I am now. So for me, buzzing isn't an option. With his teaching I am developing daily....so -as long as I progress, I am not really bothered.
The most important thing to remember about buzzing, is that for it to be an asset to your playing - you MUST buzz exactly as you do when playing on the instrument. You should be able to buzz a "g" (for example) , put the instrument on and hear a "g". Also play a "g" and take the MP and instrument off and still hear it buzzing. If you can do that - you have a "natural" embouchure. If you start buzzing in a way that isnt your usual set up - you are developing "another" embouchure.......which isn't so good.
I will in the next two weeks be starting to teach my grandson how to blow - I will start him on recorder, then get him free lip buzzing, then buzz a MP - THEN and only THEN he gets the Cornet. It will be his reward........
He will then have a fantastic start to his playing career.....a totaly free natural embouchure (he is 6 years old by the way). Those Jock McKenzie books are so good - I use them also - play along with the CD - if they seem too easy - knock it up an octave....
I do realise that this is a "red hot" subject, and people all have differing views on this........but as I see it, my comments above make total sense.
If any of this sounds a bit familiar..........my teacher is Roddy - see his Embouchure Enhancement book reviews in Tmp Review section......