There is so much for a baby to learn and to do - like getting dressed, colouring, using the potty, cutting food, catching a ball, throwing, digging, pouring, measuring, sharing, taking turns, jumping, skipping, climbing, drawing, scooping, running, pedaling...
My daughter learned to read at 2 like she learned all these other things - as a natural part of life. A lot of it was just sitting on our laps reading books she loved, especially ones where she followed along "reading" the rebus-like pictures like in the book about the horse looking for where all the apples went. The alphabet she learned by singing and because at day care there was the alphabet along the wall.
This way, she learned it like everything else and it became a deep part of herself. The goal was not to "teach her to read." But she learned anyway - sounding words out, and was thus reading "The Little House on the Prairie" series as she turned 4 and "Anne of Green Gables" & "Little Women" series at 5.
BUT There is a downside to this! Think about the newspaper. It is very scary! We had a two year old questioning what was in the paper. There are very scary things written everywhere, and I never thought I would EVER censor what my child would read, but at such a young age, I had to, especially since she could speed read at 4 faster than I can read. You have to be really careful. That's a big downside. You have to be careful. I had to make sure she didn't read even the books her older sister read for pleasure or for school (except textbooks) because there is dark contenet not suitable for a toddler/preschooler. They are not emotionally ready for the content even though they can read it. (The upside was that at 5 she could help her 8th grade sister with homework).
Oh well. I didn't even know there was a way to teach two year olds to read books on purpose. But we all expose them to a rich variety, and I see nothing wrong with it as long as we don't get frustrated with letting them go - or not go - at their own pace in whatever particular area... unless its an LD... sigh... and then it is work work work on that area.