My parents were never militant like that with me, but basically taught me the same lesson. When I bought my Maxima ten years ago, I wrote a check for it. And now I'm waiting a little bit longer until I can write a check for my MINI.
Once you start on financing, you'll never break the cycle. And, over time, you'll resent paying for something that is old, and broken, but still costing you the same thing each month. Moreover, of course, you'll be paying 50% more for it.
And while you're making those payments for years on your car, there'll be no money for things like replacing your crusty, ancient, unbearable 600MHz Pentium III.
Parents aren't EVIL... they just recognize that some of life's lessons are about compromise, and our inability to always have what we want right away. But ultimately, this particular lesson is about having MORE of what you want, over the course of your life, rather than merely all of it right now at the expense of your future.
...and no, I'm not a parent.
Still young.
-wynn