D.T.
I HIGHLY recommend reading the book "Einstein Never Used Flashcards". It goes over dozens of scientific tests that prove that the best way for a child to learn is to put them in a room with a few other children and a bunch of open-ended toys (blocks, balls, legos, cars, etc). They will learn problem-solving.
Yes, you can teach your toddler/preschooler to read. HOWEVER... they are simply memorizing at that point. They do not learn to LEARN... and children need to learn how to learn new things. How to experiment. How to come up with ideas and be secure enough to try them. How to not be afraid of failure and simply go on to another idea when the first one (or 2nd or 5th or 10th) doesn't work.
Numerous tests have proved that by age 8 or 9 (basically 3rd grade) all kids are EQUAL. OK... not all... but in 99.9% of the cases, you can't look at reading ability to tell which kid was reading at 2 years old and which one learned in kindergarten. You can tell the difference... but not in a good way. The kids who learned the more traditional way usually scored higher on tests, had more friends, was more socially adjusted and generally more happy. (yes... surveys/tests prove this). In general, the kids who learned how to read at a young age lacked many social skills, didn't have a good imagination and was therefore 'bored' alot because they simply didn't know many different ways to play. Yes, it's a generalization and some kids are great if they learned to ready early... I'm simply saying what numerous studies have shown.
Ask any teacher and they'll tell you the most important things for a child entering kindergarten are things like standing/walking in a line, listening to teachers/adults, being able to deal with separation from the parents for the entire day, getting along and playing well with other children, taking turns, sitting quietly for 10 minutes, raising hands to talk, etc. Notice nothing academic like reading or knowing numbers.
My son went to preschool for a few years. He knew the letters of the alphabet and the sounds they made on his first day of kindergarten. Within 2 months, he was reading chapter books (along with the rest of his class... most of whom couldn't read anything the first day of school, either). If a teacher has a classroom full of children who are socially/emotionally adjusted and mature then they can teach them anything quickly.