Nothing at all. But writing "Microsoft" as "Micro$oft" is just childish and it taints your otherwise potentially valid message. Do you also refer to Windows as "Winblows" maybe?

My kid went from disinterested in the letters we taught him, to fascinated when he realized he could use them to get special blocks.

Minecraft teaches phonics. Anyway, my 4 year old can read books. He doesnt even practice the homework in his preschool because he just reads the words that everyone else sounds out.