This is a question asked on behalf of thousands of new beginner learning 漢語拼音. When giving a 漢語拼音 dictation test (like spelling test in English) to my students, one very smart student write "g" for my pronunciation of 歌. When I pointed out it's wrong, he argued: "you taught us HYPY "g" is pronounced as 歌/哥. So when I heard you pronounced 歌 and I wrote "g". What's wrong with that?" How can I reply? Especially knowing it is the biggest flaw if 漢語拼音 teaching.
元音有韵，辅音无韵。is a fundamental phonetic concept. Since HYPY barrowed English alphabets as its symbols, it should stick to the separation of the "names" of the letters and the pronunciation of the letters in spelling. The name of letter "b" is "bee", but the pronunciation is very short bursting solid sound of both lips, without any "vowel" involved. When teaching 辅音，all the material pronounced either with "e" or "o" rhyme. Wrong! Unless you remind your students that you are introducing the "names" of the symbols, followed by the right pronunciation in spelling, i.e. 辅音无韵。 Thus 歌 is rhymed, must be spelled "ge" as "e" contributes the rhyme.
Is it that the teaching method is so authoritative that no one ever pointed out its flaw? BTW, what's wrong with 声母 and 韵母 that they must be changed to 辅音 and 元音？
Because the consonants, aka initials, in Chinese Pinyin don't work they do in English. When Chinese pupils are learning the alphabet for pinyin, teachers won't teach the standard English pronunciations for all the letters. Instead, they would categorise initials into several categories:
b p m f - all are given an extra final [wo] (we shouldn't see it as a vowel because it contains a [w] pronunciation)
d t n l g k h - all are given an extra final [ə]
You can find more details in the Wiki page: https://en.wikipedia.org/wiki/Pinyin, where initials are set into several groups by different colours.
b p m f
d t n l
g k h
j q x
z c s r
zh ch sh