Ok, every one has a different opinon, but this is a pretty terrible idea for a beginner.
Your non-thumb chords are buzzing because your fingers are not strong enough and not accurate enough to play a chord properly. Guess what? Until they get strong and accurate enough, everything you play will sound like shit.
There are no short cuts to this, you need to develop your fingers.
I play with the thumb over the top when it is needed, but it offers a massive disadvantage and only two very, very minor advantages.
The critical disadvantage and the one you'll run into in a few months when you start being able to play more than two chords smoothly is that it severely changes the angle of your fingers on the fret board. You have so much less space to work with if your thumb is over the top, and this reduces your fingers' ability to do their job. They need to be coming down at 90 degrees, or as close as you can to it.
Two reasons for this: 1) so they don't inadvetently hit other strings and cause even more buzz and 2) so you move them quickly and strongly to another note. Learn the rhythm guitar intro to Wish you were here. Play the G with your thumb and your chances of hitting those hammerons cleanly are seriously reduced. Worse, your abilty to smoothly go from the bass G note to the A-B hammer are almost non existent. You have no space to work with, and you need your thumb in the middle on the neck to have the pivot to hit those hammerons hard.
The only times I use the thumb is so I can comfortably stretch to another note or need to bend the fuck out of another note - say using the thumb to fret the B on the low E while soloing on the higher strings. But as my pinky is getting pretty strong and accurate lately, I'm finding I can just barre the 7th and get the same sound. In a year I'll only be doing it to look cool.
The other time I use it is to slide on the low E when holding a chord, Like Lightning Hopkins does in this.
So while it can be useful at time, it really is very limiting if used as the basis of a technique.
TL/DR: No.