I don't think that's actually the case. When I'm reading, I'm reading sentences or paragraphs at a time (not letters at a time), regularly making significant guesses on word sound and meaning based on context clues. I think this is true of most adept readers. Clearly understanding individual letters is part of that, but would not agree that "phonics" == "reading"
It's a lttile mroe colmceptiad tahn taht toguhh. Yes, iuiivadndl ltteres do metatr, but good rdreeas aern't mtenally snidunog out eervy wrod tehy raed. Raehtr, thier eeys tkae in eevry leettr at ocne and teihr brinas intntalsy renzgioce the wrod. Taht's why you can prlaboby slitl raed tihs ppaaagrrh eevn thgouh the mdidle leetrts in ervey wrod are scerbmald.
(It's a little more complicated than that though. Yes, individual letters do matter, but good readers aren't mentally sounding out every word they read. Rather, their eyes take in every letter at once and their brains instantly recognize the word. That's why you can probably still read this paragraph even though the middle letters in every word are scrambled.)
Phonics is important for being able to read words your brain isn't already familiar with, which is especially critical during the learning process when "words your brain isn't already familiar with" is like 95% of words. Context clues can help there too, but those aren't nearly as easy or accurate as just sounding out the word.
Fun anecdote: I recently had a chance to re-experience that learning process myself after listening to a long fantasy book series on Audible with lots of made-up terms (names, cities, magic items, etc), then going on a fan forum later and seeing those same words spelled out for the first time ever. Phonics was invaluable to me in puzzling out which words corresponded to which terms I was familiar with from listening to the series.
