ethelfleda, it's not a stupid question.
The issue is long-term independence. Many children can successfully seem to read well by just memorising the look of all the words that come up in books from age 5-7, as if they were just little random pictures for each word.
However, as the complexity of the books increases, and the breadth of vocabulary increases, most of these children are going to struggle. It's easy at 7 to memorise words like "door", "and", "tin" and so on, but what about secondary education and beyond?
Firstly, the method of memorising the appearance of words means you need to have someone friendly on hand (who won't laugh at you) to tell you what it says the first time you see a word like precipitate in Chemistry in year 9.
Secondly, it is very hard work to memorise the meaning of 20,000+ squiggles shaped like dhowr, shqor, avu, and so on. Unfortunately, if you never get phonics, which is just the word for these symbols represent that sound in the word, that is what you will be doing
Not only that, but spelling tests will be very unpleasant, as to you, you're just drawing squiggles, and being told off for drawing them wrongly, because you can't remember whether stationary is ghworj or ghworlj.
Some people have amazing visual memories and may succeed anyway. Most of us don't!