You want to purchase the right equipment so you don't want to purchase intermediate equipment if you're advanced or an expert.
Equipment prices are based on performance levels. The higher performance you are, the more your equipment will cost. So why purchase more expensive equipment if you don't need it?
Another reason knowing your ability is important is safety. If you're an novice or intermediate, you'll know to stay off a black and double black runs because you could get out of control and get hurt.
Do not confuse your ability level with your skier type. They are two separate categories. Someone could be an advanced skier yet be a Skier Type 1 for binding settings.
Skier type helps shops determine your DIN settings on your bindings. Less aggressive skiers (Type I) will have lower DIN setting while more aggressive skiers (Type III) will have higher DIN settings.
Selecting your skier type is your responsibility. Your skier type, height, weight, age and ski boot sole length are used by the shop technician to determine the release / retention settings of your bindings, also referred to as the DIN setting. It is important to rovide accurate information. Inaccurate information may increase your risk of injury. Do not overstate your type or ability level.