In your playing you use the tongue to make a close aperture for playing. It does a lot of the same things as a close lip aperture. I personally find the close lip setting gives me more endurance.
Buzzing is NOT exactly about playing. It is a way to learn to use a close lip aperture.
Your example about nonbuzzers getting a bad sound if they try a buzzing embouchure is right. There are a couple of reasons here. 9 times out of 10 you aren’t really buzzing like you play. Instead you have formed a NEW embouchure. You buzz that new embouchure and it sounds bad. Given some time it clears up. It is using the muscles in a different way.
It may be easier for you to buzz if you put your lips together play a note and very slowly start removing the mouthpiece. The sudden loss of feedback will stop the buzz.
There ARE people who can buzz put the horn up and play. Then lower the horn and still be buzzing. It has a lot to do with how you were started on the horn. My 9 year old can do this but she started out buzzing and sneaking the horn into place.
Nick has written an article that explains some of this. I like his physics better than mine. Its been a long time since college (for me). And he teaches this stuff.
Buzzing helps even if you can’t hold the buzz when you remove the horn. It is a training tool.