I took shorthand many, many years ago, and I was told it ruins your spelling. I don't think it had any effect on mine. Barring some physical or mental problem, you can choose to be literate. My belief is that you're never too old to learn. And if people would just take the time to proofread what they write, it would help considerably. I think that's just a courtesy to the reader. Mistakes will always happen, but I don't like for people who read what I write to think I'm stupid. (Remember, the red lines under words have a purpose.)