Some kids will learn to read no matter how you teach them, but some kids will develop guessing habits and really struggle with reading with this kind of approach. I prefer to instill good sounding-out habits first, and work on a few sight words at a time along the way. 97% of English words can be sounded out by learning basic phonograms and the sounds they make, along with some basic rules. (Even most of the Dolch sight words are not really sight words). I like to help kids learn how to sound them out, then provide sufficient practice so they can read them fluently.
Sight-reading methods make words like house and horse (4 of the 5 same letters, same shape, same beginning and ending) look nearly identical. And if you end up with a child who guesses based on a few letters, word shape, or context…it’s hard to untrain those habits and help the child become a fluent reader.
As far as adults reading–think about the last time you tried to read a name you weren’t familiar with or a technical article that used unfamiliar vocabulary–likely you tried to sound out the word in an attempt to recognize it.