Why is it necessary to use silent letters in English if it is not considered for pronunciation?

Answer 1

If you're asking why we don't change the spelling of old words to match their current pronunciation—the reason is that some words are pronounced differently in regions of various English-speaking countries. Which spelling would be best? It would be difficult to decide. it would also require everyone to learn all new ways of spelling. For this reason, it's best to leave the spellings as they are (even though they are no longer pronounced the way they are spelled.

We are using the old spelling of words to be consistent. However, the way we say those words has changed.

Answer 2

Silent letters are diacritic which means they serve the purpose of changing the pronunciation of a syllable as in ‘tub’ and ‘tube’.

Answer 3

Because English--unlike many original languages, like Chinese, Greek or Hebrew-- derives from quite a few other languages spanning Southern, Central and Northern Europe. Therefore,most ol the words we now use in American English (versus Canadian or British) came from somewhere else.

Therefore, those words "from somewhere else" must remain true to their original language regarding spelling, grammar, and so forth--even if they are presently members of "our" own language.