Perhaps it's best to break down what belt actually is for the purpose of this blog...
Physically, "belt" is glorified chest voice. The term is primarily used in music theatre, but we see it in folk music of many lands (think spanish folk music and Teresa Berganza!), as well as certain pop/rock genres...and certainly in the African-American gospel church!
Belt is NOT yelling!!! Louder is not better. Belt appears louder only because of how the resonance balances with vowel choice.
Again, simplifying, belt uses wider resonance and wider, flatter vowel choices. In doing so, there is more elastic pull in the larynx and therefore, you need MORE air, not less, MORE support, not less, MORE suspension - and the body needs to truly be actively available or the voice will push - and it won't be belt anymore, but rather, yelling!
In making these flatter/wider vowel choices, the space of resonance and the laryngeal space needs to remain open - thus the muscles must MUST be built carefully and consistently so nothing collapses. This is careful work and behavioral work so these muscles respond to the choices we as singers are making. It is not a fluke. It is a careful rebalancing of muscles, breath and resonance. Therefore, the irony, belt is actually LEGIT!!!! It is not what untrained singers do. TRAINED and studied singers can learn the physicality of belt. Not all have the physicality to SUSTAIN belt technique consistently, but like any physical activity, anybody can learn the FORM.
Does it hurt when you belt? well, then you aren't belting...
People in the business throw out these vocal terms - belt, legit, mix, belt-mix - but do they really KNOW what they are talking about???? Could they explain it, let alone demonstrate it??? I leave that to you, the jury, to decide...I guess, rhetorically, does it matter?
It is YOUR responsibility, my dear singer/reader, to be a SMART singer - work with a teacher who can give you the WHY and HOW, and you do the work to create the behavior. Then you will never "give them what they want" but rather, "give them what you HAVE and CONVINCE them it's what they want!"
A short blog entry tonight...sweet dreams.