I think the main takeaway of this shouldn’t be that all kids will be able to read, but more that parents should not be afraid to try to teach letter sounds/blending/simple reading before kindergarten. So many parents I’ve met feel like this is “way too early” and I found many of those same parents end up tutoring their kids in kindergarten to catch up to grade level.
More recently, I’ve been teaching a 3 year old letter sounds and he loves running around finding signs saying “Dad” I found a “duh”. “Duh duh duh!” (For D). Kids really just want to hang out with you so, it’s ok to just throw in some letter sounds or number counting ideas in here and there. You’ll be surprised what they pick up!