FAO Mr Richard Bridge you are talking dangerous rubbish. Calling some harassed school teacher a frigid soprano is sexist. She at least will have passed some exams and had a lot of gruelling teaching experience before being left with a class. All you have is downright ignorance and prejudice These are not opinions but dangerous and stupid voice wrecking ideas. If used properly the voice can be worked hard for life, if not nodes on the chords can develop very quickly and wreck your singing and speaking voice.
SBP Cooperator makes some good points The point about diaphragm support is that it is not exclusively a classical technique - actors use it in live theatre to project their voice. Musical theatre singers use it. Diaphragm support means you can project your voice safely without clenching the throat - it also means the voice lasts longer - stays in tune and also you can more easily control the dynamics ie song softly with more intensity. All a mike will do is amplify your vocal weaknesses
Vocal technique is not a replacement for interpreting the text for the audience but enhances the performer by giving more options to use lyrics and melody to create a better message for the audience