Sure. Ultimately, it all comes down to preference. So yes, you could represent your min/max as separate lines, but candlestick charts are the most widely accept

Sure. Ultimately, it all comes down to preference. So yes, you could represent your min/max as separate lines, but candlestick charts are the most widely accepted means for representing volatility. That's why they're so widely used in finance. Candlesticks are also useful for giving a good visual indicator of your interval, which is another area where line charts fall down. There is no visual clue given with a line chart that shows you whether you're looking at a 5 minute interval, 1 hour interval, or 1 year interval. The thickness of a candlestick relative to the x-axis (usually time) gives a strong visual clue about the interval.