The thing is, after you have experience reading, then you do naturally use a “sight method” for reading. But you have to use the basic building blocks first—learn the approximate sound for each letter, and how the letters fit together to give a clue about the pronunciation of the word.
Written English is only semi-phonetic, so it is not completely possible to teach a pure phonetic method. (For example: phonetic is pronounced “fo ne’ dik.”)
Please note Don Potter’s favorite approach: Blend Phonics
Nobody stays at the pronunciation of letters for more than a few months. You quickly move to blends. Two-letter blends and then three-letter blends.
Once you blend, for example, F plus L plus 0 to create a new sound—flo— you no longer deal with the letters or sound them out. So a long word like “flotation” is very simple. Three common blends, and you’re done.
A word like that would almost never be mastered by a sight-word reader.
In fact one of the jokes about sight-word readers is that all long words starting with V, for example, become basically the same word. Victory, victims, Virgin, vigilant, vigilante, violent, virulent, vigorous, virtuous, virtual, Viceroy, vitamin, and many more. The poor soul has to plug in all these words until one of them seems to make sense.