That's cause your opinion was kinda stupid. A good driver is a good driver, it doesn't matter what kind of racing you do. In addition to the above examples, Jason Saini went from autocrosser straight into winning the playboy mx-5 cup. So telling someone not to autocross because it will make it harder to road race is stupid. But I also disagree with what lola said, a good road racer will have no problems running well at an autocross. Like I said before, a good driver is a good driver.
It doesn't matter what you do, you can autocross, time trial, drift, drag, road race, whatever. Just get some seat time and learn something.
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Jeremy