Well this explanation may sound "messy" but I'll try. I do buzz my lips on purpose. It's how I stay on pitch. I was taught in the "Old Days" to lip my notes in tune. Older trumpets/cornets didn't always have intonation aids so what did a player do? Lip the note in tune. How do you do that if you don't know how to control your lips? You can't and you play out of tune. If the rest of the section or band goes flat, then sharp, then flat, are you going to constantly "fix" the problem by moving your slide in and out? I do not any longer use a static embouchure as I did in high school and also when I started my comeback. I won't go into an embouchure discussion, but I no longer try to improperly use air flow and pressure to achieve my goals. There is nothing more annoying to me than to watch a self absorbed player playing a solo and CONSTANTLY messing with his tuning slide. MY GOD! HAVE THEY NO SKILLS!!!??? Phew, now I feel better. Awareness is the biggest benefit IMO to lip buzzing. In and of itself it can't make you a better player but when the two work together (playing the horn), then good things can happen.