Many years ago, we learned to spell by learning the names and sounds of letters first, then we put those letters together and formed words.
Then we read sentences with those words in them and if we didn't know the words, we couldn't read the sentence.
I remember it as being stilted and irrelevant, the stories that were used to teach us to read were boring and bore little resemblance to our personal experience.
Nowadays, rather than a rote letter by letter, word by word approach, the teaching of spelling is more student centered and individualised, using words that are (hopefully) relevant and meaningful - these words have often been taken from the children's own writing.
It is commonly believed by those who were taught spelling the traditional (rote learning) way, that if children were systematically taught all the spelling rules and letter sounds (phonics), then spelling abilities would improve dramatically.
And if it weren't for the many exceptions to these rules and the different learning needs of children, then that may be so.